diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7678193..eb5c9a6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -26,8 +26,8 @@ set(LIBS -lpcre2-8 -lpcre2-posix SDL2 imgui)
 set(IMGUI_LIBS SDL2 Freetype::Freetype)
 
 set(INCLUDES imgui imgui/backends imgui/misc/cpp imgui/freetype /usr/include/SDL2)
-set(SOURCES main.cpp event_loop.cpp logcat_thread.cpp logcat_entry.cpp log.cpp config.cpp misc.cpp pcre2_wrapper.cpp
-    windows/logs.cpp windows/settings.cpp windows/main.cpp)
+set(SOURCES main.cpp event_loop.cpp logcat_thread.cpp logcat_entry.cpp log.cpp config.cpp filters.cpp misc.cpp pcre2_wrapper.cpp
+    group_panel.cpp windows/logs.cpp windows/settings.cpp windows/filters.cpp windows/main.cpp)
 set(IMGUI_SOURCES imgui/imgui.cpp imgui/imgui_draw.cpp imgui/imgui_widgets.cpp imgui/imgui_tables.cpp
     imgui/misc/cpp/imgui_stdlib.cpp imgui/misc/freetype/imgui_freetype.cpp
     imgui/backends/imgui_impl_sdl.cpp imgui/backends/imgui_impl_opengl3.cpp)
@@ -42,7 +42,8 @@ endif()
 
 set(FLAGS "${FLAGS} -DIMGUI_USER_CONFIG='\"../myimconfig.h\"'")
 # https://t.me/NightShadowsHangout/670691
-set(FLAGS "${FLAGS} -Werror -Wall -Wextra -Wshadow -Wpedantic -Wno-gnu-anonymous-struct -fno-rtti -fPIC -Wconversion -Wno-unused-parameter -Wimplicit-fallthrough")
+# https://t.me/NightShadowsHangout/688372
+set(FLAGS "${FLAGS} -Werror -Wall -Wextra -Wshadow -Wpedantic -Wno-gnu-anonymous-struct -fPIC -Wconversion -Wno-unused-parameter -Wimplicit-fallthrough")
 # https://sourceforge.net/p/valgrind/mailman/valgrind-users/thread/Ygze8PzaQAYWlKDj%40wildebeest.org/
 set(FLAGS "${FLAGS} -gdwarf-4")
 
diff --git a/config.h b/config.h
index 33d490e..0b8f545 100644
--- a/config.h
+++ b/config.h
@@ -12,9 +12,3 @@ std::string get_config_folder();
 void create_config_folders_if_necessary();
 Config load_config();
 void write_config(const Config& config);
-
-constexpr bool operator!=(const Config& lhs, const Config& rhs) {
-    return lhs.logcat_command != rhs.logcat_command
-        || lhs.normal_font_size != rhs.normal_font_size
-        || lhs.monospace_font_size != rhs.monospace_font_size;
-}
diff --git a/event_loop.cpp b/event_loop.cpp
index 93b8c80..a8d0eea 100644
--- a/event_loop.cpp
+++ b/event_loop.cpp
@@ -2,23 +2,29 @@
 
 #include "log.h"
 #include "config.h"
+#include "filters.h"
 #include "logcat_thread.h"
 
 #include "windows/logs.h"
+#include "windows/filters.h"
 #include "windows/settings.h"
 #include "windows/main.h"
 #ifndef NDEBUG
     #include "windows/debug.h"
 #endif
 
-static inline void check_for_logcat_items(LogcatThread& logcat_thread, std::vector<LogcatEntry>& filtered_logcat_entries) {
+static inline void check_for_logcat_items(LogcatThread& logcat_thread, const Filters& filters,
+        std::vector<LogcatEntry>& logcat_entries, std::vector<size_t>& filtered_logcat_entry_offsets) {
     LogcatThreadItem* logcat_thread_item;
 
     while ((logcat_thread_item = logcat_thread.atomic_ring_buffer.get())) {
         if (std::holds_alternative<std::string>(*logcat_thread_item)) {
             log_raw(std::move(std::get<std::string>(*logcat_thread_item)), false);
         } else if (std::holds_alternative<LogcatEntry>(*logcat_thread_item)) {
-            filtered_logcat_entries.push_back(std::move(std::get<LogcatEntry>(*logcat_thread_item)));
+            logcat_entries.push_back(std::move(std::get<LogcatEntry>(*logcat_thread_item)));
+            if (matches(filters, logcat_entries.back())) {
+                filtered_logcat_entry_offsets.push_back(logcat_entries.size() - 1);
+            }
         } else {
             throw std::runtime_error("Cannot handle all possible logcat thread item variants");
         }
@@ -27,14 +33,17 @@ static inline void check_for_logcat_items(LogcatThread& logcat_thread, std::vect
 }
 
 
-void event_loop(ImFont* monospace_font, Config& active_config, LogcatThread& logcat_thread, bool* run_event_loop) {
+void event_loop(ImFont* monospace_font, Config& active_config, Filters& active_filters, LogcatThread& logcat_thread, bool* run_event_loop) {
     static Config inactive_config;
+    static Filters inactive_filters;
     static bool show_settings_window = false;
+    static bool show_filters_window = false;
     static bool show_logs_window = false;
     static size_t log_entries_read = 0;
-    static std::vector<LogcatEntry> filtered_logcat_entries;
+    static std::vector<LogcatEntry> logcat_entries;
+    static std::vector<size_t> filtered_logcat_entry_offsets;
 
-    check_for_logcat_items(logcat_thread, filtered_logcat_entries);
+    check_for_logcat_items(logcat_thread, active_filters, logcat_entries, filtered_logcat_entry_offsets);
 
 #ifndef NDEBUG
     debug_window(logcat_thread);
@@ -44,6 +53,10 @@ void event_loop(ImFont* monospace_font, Config& active_config, LogcatThread& log
         settings_window(active_config, inactive_config, &show_settings_window);
     }
 
+    if (show_filters_window) {
+        filters_window(active_filters, inactive_filters, logcat_entries, filtered_logcat_entry_offsets, &show_filters_window);
+    }
+
     if (show_logs_window) {
         bool autoscrolling = false;
         logs_window(monospace_font, &autoscrolling, &show_logs_window);
@@ -53,8 +66,9 @@ void event_loop(ImFont* monospace_font, Config& active_config, LogcatThread& log
     }
 
     // log_entries must not be mutated until the show logs button
-    main_window(log_entries_read == log_entries.size(),
-        monospace_font, filtered_logcat_entries,
-        active_config, inactive_config, &show_settings_window,
-        &show_logs_window, run_event_loop);
+    main_window(log_entries_read == log_entries.size(), monospace_font,
+        logcat_entries, filtered_logcat_entry_offsets,
+        active_config, inactive_config,
+        active_filters, inactive_filters,
+        &show_settings_window, &show_filters_window, &show_logs_window, run_event_loop);
 }
diff --git a/event_loop.h b/event_loop.h
index 683a7f3..2bbf0fd 100644
--- a/event_loop.h
+++ b/event_loop.h
@@ -3,6 +3,7 @@
 #include <imgui.h>
 
 #include "config.h"
+#include "filters.h"
 #include "logcat_thread.h"
 
-void event_loop(ImFont* monospace_font, Config& active_config, LogcatThread& logcat_thread, bool* run_event_loop);
+void event_loop(ImFont* monospace_font, Config& active_config, Filters& active_filters, LogcatThread& logcat_thread, bool* run_event_loop);
diff --git a/filters.cpp b/filters.cpp
new file mode 100644
index 0000000..520cb70
--- /dev/null
+++ b/filters.cpp
@@ -0,0 +1,275 @@
+#include <string>
+#include <vector>
+#include <stdexcept>
+
+#include "log.h"
+#include "filters.h"
+
+Filter::~Filter() {
+}
+
+
+IntegerFilter::IntegerFilter(FilterKey key_, size_t other_, bool inverted_, bool disabled)
+        : key(key_), other(other_), inverted(inverted_), _disabled(disabled) {
+    if (key_ != FilterKey::PID && key_ != FilterKey::TID) {
+        throw std::runtime_error("IntegerFilter is passed a non-integer key");
+    }
+}
+
+void IntegerFilter::updated() {
+}
+
+bool IntegerFilter::disabled() const {
+    return this->_disabled;
+}
+
+void IntegerFilter::disabled(bool disabled) {
+    this->_disabled = disabled;
+}
+
+std::unique_ptr<Filter> IntegerFilter::clone() const {
+    return std::make_unique<IntegerFilter>(this->key, this->other, this->inverted, this->_disabled);
+}
+
+const std::string* IntegerFilter::error() const {
+    return nullptr;
+}
+
+bool IntegerFilter::match(const LogcatEntry& entry) const {
+    bool matched;
+    switch (this->key) {
+        case FilterKey::PID: matched = entry.pid == this->other; break;
+        case FilterKey::TID: matched = entry.tid == this->other; break;
+        default: throw std::runtime_error("IntegerFilter::match received unhandled key");
+    };
+    return !this->inverted ? matched : !matched;
+}
+
+
+StringFilter::StringFilter(FilterKey key_, std::string other_, bool inverted_, bool disabled)
+        : key(key_), other(std::move(other_)), inverted(inverted_), _disabled(disabled) {
+    if (key_ != FilterKey::User && key_ != FilterKey::Tag && key_ != FilterKey::Message) {
+        throw std::runtime_error("StringFilter is passed a non-string key");
+    }
+    this->updated();
+}
+
+void StringFilter::updated() {
+    this->_regex.reset();
+    this->_error.clear();
+
+    if (this->other.empty()) {
+        this->_error = "String must not be empty";
+        return;
+    }
+    if (!this->other.starts_with("regex:")) {
+        return;
+    }
+    if (this->other.size() == 6) {
+        this->_error = "Regex must not be empty";
+        return;
+    }
+
+    try {
+        this->_regex.emplace(&this->other.c_str()[6]);
+    } catch (const std::exception& e) {
+        this->_error = e.what();
+    }
+}
+
+bool StringFilter::disabled() const {
+    return this->_disabled;
+}
+
+void StringFilter::disabled(bool disabled) {
+    this->_disabled = disabled;
+}
+
+std::unique_ptr<Filter> StringFilter::clone() const {
+    return std::make_unique<StringFilter>(this->key, this->other, this->inverted, this->_disabled);
+}
+
+const std::string* StringFilter::error() const {
+    return !this->_error.empty() ? &this->_error : nullptr;
+}
+
+bool StringFilter::match(const LogcatEntry& entry) const {
+    bool matched;
+
+    if (this->error()) {
+        log(std::string("StringFilter::match called despite there being an error: ") + *this->error());
+        return true;
+    }
+    if (!this->other.starts_with("regex:")) {
+        switch (this->key) {
+            case FilterKey::User: matched = entry.user.value_or("") == this->other; break;
+            case FilterKey::Tag: matched = entry.tag == this->other; break;
+            case FilterKey::Message: matched = entry.message == this->other; break;
+            default: throw std::runtime_error("StringFilter::match received unhandled key");
+        }
+        return !this->inverted ? matched : !matched;
+    }
+    if (!this->_regex) {
+        log("StringFilter::match called with a regex despite there being no regex");
+        return true;
+    }
+
+    std::string str;
+    regmatch_t pmatch[1];
+    switch (this->key) {
+        case FilterKey::User: str = entry.user.value_or(""); break;
+        case FilterKey::Tag: str = entry.tag; break;
+        case FilterKey::Message: str = entry.message; break;
+        default: throw std::runtime_error("StringFilter::match received unhandled key");
+    }
+    pmatch[0].rm_so = 0;
+    pmatch[0].rm_eo = static_cast<regoff_t>(str.size());
+
+    matched = this->_regex->match(str.data(), 1, pmatch, REG_STARTEND)
+        && pmatch[0].rm_so == 0 && static_cast<size_t>(pmatch[0].rm_eo) == str.size();
+    return !this->inverted ? matched : !matched;
+}
+
+
+BufferFilter::BufferFilter(unsigned int wanted_, bool disabled) : wanted(wanted_), _disabled(disabled) {
+}
+
+void BufferFilter::updated() {
+}
+
+bool BufferFilter::disabled() const {
+    return this->_disabled;
+}
+
+void BufferFilter::disabled(bool disabled) {
+    this->_disabled = disabled;
+}
+
+std::unique_ptr<Filter> BufferFilter::clone() const {
+    return std::make_unique<BufferFilter>(this->wanted, this->_disabled);
+}
+
+const std::string* BufferFilter::error() const {
+    return nullptr;
+}
+
+bool BufferFilter::match(const LogcatEntry& entry) const {
+    return this->wanted & static_cast<unsigned int>(entry.buffer) || this->wanted == 0;
+}
+
+
+PriorityFilter::PriorityFilter(unsigned int wanted_, bool disabled) : wanted(wanted_), _disabled(disabled) {
+}
+
+void PriorityFilter::updated() {
+}
+
+bool PriorityFilter::disabled() const {
+    return this->_disabled;
+}
+
+void PriorityFilter::disabled(bool disabled) {
+    this->_disabled = disabled;
+}
+
+std::unique_ptr<Filter> PriorityFilter::clone() const {
+    return std::make_unique<PriorityFilter>(this->wanted, this->_disabled);
+}
+
+const std::string* PriorityFilter::error() const {
+    return nullptr;
+}
+
+bool PriorityFilter::match(const LogcatEntry& entry) const {
+    return this->wanted & static_cast<unsigned int>(entry.priority) || this->wanted == 0;
+}
+
+
+GroupFilter::GroupFilter(std::vector<std::unique_ptr<Filter>> filters_, GroupFilter::Type type_, bool disabled)
+        : filters(std::move(filters_)), type(type_), _disabled(disabled) {
+}
+
+void GroupFilter::updated() {
+}
+
+bool GroupFilter::disabled() const {
+    return this->_disabled;
+}
+
+void GroupFilter::disabled(bool disabled) {
+    this->_disabled = disabled;
+}
+
+std::unique_ptr<Filter> GroupFilter::clone() const {
+    std::vector<std::unique_ptr<Filter>> new_filters;
+    new_filters.reserve(this->filters.size());
+
+    for (const std::unique_ptr<Filter>& filter : this->filters) {
+        new_filters.push_back(filter->clone());
+    }
+
+    return std::make_unique<GroupFilter>(std::move(new_filters), this->type, this->_disabled);
+}
+
+const std::string* GroupFilter::error() const {
+    return nullptr;
+}
+
+bool GroupFilter::match(const LogcatEntry& entry) const {
+    bool had_matched = false;
+
+    for (const std::unique_ptr<Filter>& filter : this->filters) {
+        if (filter->disabled() || filter->error()) {
+            continue;
+        }
+
+        bool matched = filter->match(entry);
+        if (this->type == GroupFilter::Type::Any && matched) {
+            return true;
+        } else if (this->type == GroupFilter::Type::None && matched) {
+            return false;
+        } else if (this->type == GroupFilter::Type::All && !matched) {
+            return false;
+        } else if (this->type == GroupFilter::Type::One) {
+            if (had_matched && matched) {
+                return false;
+            }
+            if (matched) {
+                had_matched = true;
+            }
+        }
+    }
+
+    if (this->type == GroupFilter::Type::Any) {
+        return false;
+    } else if (this->type == GroupFilter::Type::One && !had_matched) {
+        return false;
+    }
+    return true;
+}
+
+
+void copy_filters(Filters& filters, const Filters& other) {
+    filters.clear();
+    filters.reserve(other.size());
+
+    for (const auto &[title, filter] : other) {
+        filters.push_back(std::make_pair(title, filter->clone()));
+    }
+}
+
+bool matches(const Filters& filters, const LogcatEntry& entry) {
+    bool ok_filter_exists = false;
+
+    for (const auto &[title, filter] : filters) {
+        if (filter->disabled() || filter->error()) {
+            continue;
+        }
+        ok_filter_exists = true;
+        if (filter->match(entry)) {
+            return true;
+        }
+    }
+
+    return !ok_filter_exists;
+}
diff --git a/filters.h b/filters.h
new file mode 100644
index 0000000..ba34099
--- /dev/null
+++ b/filters.h
@@ -0,0 +1,140 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <memory>
+#include <utility>
+
+#include "logcat_entry.h"
+#include "pcre2_wrapper.h"
+
+enum class FilterKey {
+    Buffer,
+    User,
+    PID,
+    TID,
+    Priority,
+    Tag,
+    Message,
+};
+
+class Filter {
+public:
+    // https://stackoverflow.com/a/10024812
+    virtual ~Filter() = 0;
+
+    virtual void updated() = 0;
+    virtual bool disabled() const = 0;
+    virtual void disabled(bool disabled) = 0;
+    // https://stackoverflow.com/a/65344294
+    virtual std::unique_ptr<Filter> clone() const = 0;
+    virtual const std::string* error() const = 0;
+    virtual bool match(const LogcatEntry& entry) const = 0;
+};
+
+class IntegerFilter : public Filter {
+public:
+    IntegerFilter(FilterKey key_, size_t other_, bool inverted_ = false, bool disabled = false);
+
+    void updated() override;
+    bool disabled() const override;
+    void disabled(bool disabled) override;
+    std::unique_ptr<Filter> clone() const override;
+    const std::string* error() const override;
+    bool match(const LogcatEntry& entry) const override;
+
+    FilterKey key;
+    size_t other;
+    bool inverted;
+
+private:
+    bool _disabled;
+};
+
+class StringFilter : public Filter {
+public:
+    // https://stackoverflow.com/a/2173764
+    StringFilter(const StringFilter&) = delete;
+    StringFilter& operator=(const StringFilter&) = delete;
+
+    StringFilter(FilterKey key_, std::string other_, bool inverted_ = false, bool disabled = false);
+
+    void updated() override;
+    bool disabled() const override;
+    void disabled(bool disabled) override;
+    std::unique_ptr<Filter> clone() const override;
+    const std::string* error() const override;
+    bool match(const LogcatEntry& entry) const override;
+
+    FilterKey key;
+    std::string other;
+    bool inverted;
+
+private:
+    std::string _error;
+    std::optional<Pcre2Regex> _regex;
+    bool _disabled;
+};
+
+class BufferFilter : public Filter {
+public:
+    BufferFilter(unsigned int wanted_, bool disabled = false);
+
+    void updated() override;
+    bool disabled() const override;
+    void disabled(bool disabled) override;
+    std::unique_ptr<Filter> clone() const override;
+    const std::string* error() const override;
+    bool match(const LogcatEntry& entry) const override;
+
+    unsigned int wanted;
+
+private:
+    bool _disabled;
+};
+
+class PriorityFilter : public Filter {
+public:
+    PriorityFilter(unsigned int wanted_, bool disabled = false);
+
+    void updated() override;
+    bool disabled() const override;
+    void disabled(bool disabled) override;
+    std::unique_ptr<Filter> clone() const override;
+    const std::string* error() const override;
+    bool match(const LogcatEntry& entry) const override;
+
+    unsigned int wanted;
+
+private:
+    bool _disabled;
+};
+
+class GroupFilter : public Filter {
+public:
+    enum class Type {
+        All = 0,
+        Any = 1,
+        One = 2,
+        None = 3,
+    };
+
+    GroupFilter(std::vector<std::unique_ptr<Filter>> filters_, Type type_, bool disabled = false);
+
+    void updated() override;
+    bool disabled() const override;
+    void disabled(bool disabled) override;
+    std::unique_ptr<Filter> clone() const override;
+    const std::string* error() const override;
+    bool match(const LogcatEntry& entry) const override;
+
+    std::vector<std::unique_ptr<Filter>> filters;
+    Type type;
+
+private:
+    bool _disabled;
+};
+
+typedef std::vector<std::pair<std::string, std::unique_ptr<Filter>>> Filters;
+void copy_filters(Filters& filters, const Filters& other);
+bool matches(const Filters& filters, const LogcatEntry& entry);
diff --git a/group_panel.cpp b/group_panel.cpp
new file mode 100644
index 0000000..24c1dfb
--- /dev/null
+++ b/group_panel.cpp
@@ -0,0 +1,97 @@
+#define IMGUI_DEFINE_MATH_OPERATORS
+#include <imgui_internal.h>
+#include "group_panel.h"
+
+// The following code is slightly modified public domain code from https://github.com/thedmd
+// All modifications have an inline comment with "[CUSTOM]"
+// Public domain claim from https://github.com/ocornut/imgui/issues/1496#issuecomment-1287772456
+// Code from https://github.com/ocornut/imgui/issues/1496#issuecomment-569892444 and
+// some snippets from https://github.com/ocornut/imgui/issues/1496#issuecomment-655048353
+
+void ImGui::BeginGroupPanel(const ImVec2& size) // [CUSTOM]
+{
+    ImGui::BeginGroup();
+
+    //auto cursorPos = ImGui::GetCursorScreenPos(); // [CUSTOM]
+    auto itemSpacing = ImGui::GetStyle().ItemSpacing;
+    ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(0.0f, 0.0f));
+    ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(0.0f, 0.0f));
+
+    auto frameHeight = ImGui::GetFrameHeight();
+    ImGui::BeginGroup();
+
+    ImVec2 effectiveSize = size;
+    if (size.x < 0.0f)
+        effectiveSize.x = ImGui::GetContentRegionAvail().x; // [CUSTOM]
+    else
+        effectiveSize.x = size.x;
+    ImGui::Dummy(ImVec2(effectiveSize.x, 0.0f));
+
+    ImGui::Dummy(ImVec2(frameHeight, 0.0f)); // [CUSTOM]
+    ImGui::SameLine(0.0f, 0.0f);
+    ImGui::BeginGroup();
+    ImGui::Dummy(ImVec2(frameHeight, 0.0f)); // [CUSTOM]
+    ImGui::SameLine(0.0f, 0.0f);
+    //ImGui::TextUnformatted(name); // [CUSTOM]
+    ImGui::SameLine(0.0f, 0.0f);
+    ImGui::Dummy(ImVec2(0.0, frameHeight + itemSpacing.y));
+    ImGui::BeginGroup();
+
+    ImGui::PopStyleVar(2);
+
+    //ImGui::GetCurrentWindow()->ContentsRegionRect.Max.x -= frameHeight * 0.5f; // [CUSTOM]
+    ImGui::GetCurrentWindow()->ContentRegionRect.Max.x -= frameHeight * 0.5f;
+    ImGui::GetCurrentWindow()->WorkRect.Max.x          -= frameHeight * 0.5f;
+    ImGui::GetCurrentWindow()->InnerRect.Max.x         -= frameHeight * 0.5f;
+    ImGui::GetCurrentWindow()->Size.x                   -= frameHeight;
+
+    auto itemWidth = ImGui::CalcItemWidth();
+    ImGui::PushItemWidth(ImMax(0.0f, itemWidth - frameHeight));
+    //ImGui::PushItemWidth(effectiveSize.x - frameHeight); // [CUSTOM]
+}
+
+void ImGui::EndGroupPanel()
+{
+    ImGui::PopItemWidth();
+
+    auto itemSpacing = ImGui::GetStyle().ItemSpacing;
+
+    ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(0.0f, 0.0f));
+    ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(0.0f, 0.0f));
+
+    auto frameHeight = ImGui::GetFrameHeight();
+
+    ImGui::EndGroup();
+
+    //ImGui::GetWindowDrawList()->AddRectFilled(ImGui::GetItemRectMin(), ImGui::GetItemRectMax(), IM_COL32(0, 255, 0, 64), 4.0f);
+
+    ImGui::EndGroup();
+
+    ImGui::SameLine(0.0f, 0.0f);
+    ImGui::Dummy(ImVec2(frameHeight * 0.5f, 0.0f));
+    ImGui::Dummy(ImVec2(0.0, frameHeight - itemSpacing.y)); // [CUSTOM]
+
+    ImGui::EndGroup();
+
+    auto itemMin = ImGui::GetItemRectMin();
+    auto itemMax = ImGui::GetItemRectMax();
+    //ImGui::GetWindowDrawList()->AddRectFilled(itemMin, itemMax, IM_COL32(255, 0, 0, 64), 4.0f);
+
+    ImVec2 halfFrame = ImVec2(frameHeight * 0.25f, frameHeight) * 0.5f;
+    ImGui::GetWindowDrawList()->AddRect(
+        itemMin + halfFrame, itemMax - ImVec2(halfFrame.x, 0.0f),
+        ImColor(ImGui::GetStyleColorVec4(ImGuiCol_Border)),
+        halfFrame.x);
+
+    ImGui::PopStyleVar(2);
+
+    //ImGui::GetCurrentWindow()->ContentsRegionRect.Max.x += frameHeight * 0.5f; // [CUSTOM]
+    ImGui::GetCurrentWindow()->ContentRegionRect.Max.x += frameHeight * 0.5f;
+    ImGui::GetCurrentWindow()->WorkRect.Max.x          += frameHeight * 0.5f;
+    ImGui::GetCurrentWindow()->InnerRect.Max.x         += frameHeight * 0.5f;
+    ImGui::GetCurrentWindow()->Size.x                   += frameHeight;
+
+    ImGui::Dummy(ImVec2(0.0f, 0.0f));
+
+    ImGui::EndGroup();
+}
diff --git a/group_panel.h b/group_panel.h
new file mode 100644
index 0000000..13e57af
--- /dev/null
+++ b/group_panel.h
@@ -0,0 +1,13 @@
+#pragma once
+
+#include <imgui.h>
+
+// The following code is slightly modified public domain code from https://github.com/thedmd
+// All modifications have an inline comment with "[CUSTOM]"
+// Public domain claim from https://github.com/ocornut/imgui/issues/1496#issuecomment-1287772456
+// Code from https://github.com/ocornut/imgui/issues/1496#issuecomment-655048353
+
+namespace ImGui { // [CUSTOM]
+void BeginGroupPanel(const ImVec2& size = ImVec2(-1.0f, -1.0f)); // [CUSTOM]
+void EndGroupPanel();
+}; // namespace ImGui // [CUSTOM]
diff --git a/main.cpp b/main.cpp
index ff35cf7..c311bb9 100644
--- a/main.cpp
+++ b/main.cpp
@@ -16,12 +16,15 @@
 #include "log.h"
 #include "fonts.h"
 #include "config.h"
+#include "filters.h"
 #include "event_loop.h"
 #include "logcat_thread.h"
 
 int main(int, char**) {
     setlocale(LC_TIME, "");
 
+    // TODO add saving
+    Filters filters;
     Config config;
     try {
         config = load_config();
@@ -161,7 +164,7 @@ int main(int, char**) {
         ImGui_ImplSDL2_NewFrame();
         ImGui::NewFrame();
 
-        event_loop(monospace_font, config, logcat_thread, &run_event_loop);
+        event_loop(monospace_font, config, filters, logcat_thread, &run_event_loop);
 
         // Rendering
         ImGui::Render();
diff --git a/windows/filters.cpp b/windows/filters.cpp
new file mode 100644
index 0000000..a91de4e
--- /dev/null
+++ b/windows/filters.cpp
@@ -0,0 +1,257 @@
+#include <imgui.h>
+#include <imgui_stdlib.h>
+
+#include "../group_panel.h"
+#include "../filters.h"
+#include "filters.h"
+
+static inline void render_integer_filter(IntegerFilter* filter);
+static inline void render_string_filter(StringFilter* filter);
+static inline void render_buffer_filter(BufferFilter* filter);
+static inline void render_priority_filter(PriorityFilter* filter);
+static inline void render_group_filter(GroupFilter* filter);
+static inline std::unique_ptr<Filter> render_add_filter_popup();
+static void update_logcat_entries(const Filters& filters,
+        const std::vector<LogcatEntry>& logcat_entries, std::vector<size_t>& filtered_logcat_entry_offsets);
+
+static void render_filter(Filter* filter, std::string* title, bool* request_removal) {
+    ImGui::PushID(filter);
+    ImGui::BeginGroupPanel();
+
+    if (title) {
+        ImGui::AlignTextToFramePadding();
+        ImGui::Text("Title:%s%s", title->empty() ? "" : " ", title->c_str());
+        ImGui::SameLine();
+        std::string change_title_id = std::string("changefiltertitle_") + std::to_string(reinterpret_cast<size_t>(filter));
+        if (ImGui::Button("Edit")) {
+            ImGui::OpenPopup(change_title_id.c_str());
+        }
+        if (ImGui::BeginPopup(change_title_id.c_str())) {
+            ImGui::InputText("##title", title);
+            ImGui::EndPopup();
+        }
+        ImGui::SameLine();
+    }
+
+    if (ImGui::Button("Remove")) {
+        *request_removal = true;
+    }
+
+    {
+        ImGui::SameLine();
+        bool disabled = filter->disabled();
+        if (ImGui::Checkbox("Disabled", &disabled)) {
+            filter->disabled(disabled);
+        }
+    }
+
+    {
+        StringFilter* sfilter = dynamic_cast<StringFilter*>(filter);
+        IntegerFilter* ifilter = !sfilter ? dynamic_cast<IntegerFilter*>(filter) : nullptr;
+        if (sfilter || ifilter) {
+            ImGui::SameLine();
+            ImGui::Checkbox("Inverted", sfilter ? &sfilter->inverted : &ifilter->inverted);
+        }
+    }
+
+    if (filter->error()) {
+        ImGui::SameLine();
+        ImGui::Text("(%s)", filter->error()->c_str());
+    }
+
+    if (IntegerFilter* ifilter = dynamic_cast<IntegerFilter*>(filter)) {
+        render_integer_filter(ifilter);
+    } else if (StringFilter* sfilter = dynamic_cast<StringFilter*>(filter)) {
+        render_string_filter(sfilter);
+    } else if (BufferFilter* bfilter = dynamic_cast<BufferFilter*>(filter)) {
+        render_buffer_filter(bfilter);
+    } else if (PriorityFilter* pfilter = dynamic_cast<PriorityFilter*>(filter)) {
+        render_priority_filter(pfilter);
+    } else if (GroupFilter* gfilter = dynamic_cast<GroupFilter*>(filter)) {
+        render_group_filter(gfilter);
+    } else {
+        ImGui::TextUnformatted("An unknown filter, this probably shouldn't be mutated");
+    }
+
+    ImGui::EndGroupPanel();
+    ImGui::PopID();
+}
+
+static inline void render_integer_filter(IntegerFilter* filter) {
+    const char* head;
+    switch (filter->key) {
+        case FilterKey::PID: head = "PID"; break;
+        case FilterKey::TID: head = "TID"; break;
+        default: head = "Something";
+    };
+
+    ImGui::AlignTextToFramePadding();
+    ImGui::Text("%s is%s", head, filter->inverted ? " not" : "");
+    ImGui::SameLine();
+    if (ImGui::InputScalar("##int", ImGuiDataType_U64, &filter->other)) {
+        filter->updated();
+    }
+}
+
+static inline void render_string_filter(StringFilter* filter) {
+    const char* head;
+    switch (filter->key) {
+        case FilterKey::User: head = "User"; break;
+        case FilterKey::Tag: head = "Tag"; break;
+        case FilterKey::Message: head = "Message"; break;
+        default: head = "Something";
+    };
+
+    ImGui::AlignTextToFramePadding();
+    ImGui::Text("%s is%s", head, filter->inverted ? " not" : "");
+    ImGui::SameLine();
+    if (ImGui::InputText("##str", &filter->other)) {
+        filter->updated();
+    }
+}
+
+static inline void render_buffer_filter(BufferFilter* filter) {
+    auto update_if_needed = [&](bool updated) {
+        if (updated) {
+            filter->updated();
+        }
+    };
+    ImGui::AlignTextToFramePadding();
+    ImGui::TextUnformatted("Buffer is:"); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Unknown", &filter->wanted, static_cast<unsigned int>(Buffer::Unknown))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Main", &filter->wanted, static_cast<unsigned int>(Buffer::Main))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("System", &filter->wanted, static_cast<unsigned int>(Buffer::System))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Radio", &filter->wanted, static_cast<unsigned int>(Buffer::Radio))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Events", &filter->wanted, static_cast<unsigned int>(Buffer::Events))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Crash", &filter->wanted, static_cast<unsigned int>(Buffer::Crash)));
+}
+
+static inline void render_priority_filter(PriorityFilter* filter) {
+    auto update_if_needed = [&](bool updated) {
+        if (updated) {
+            filter->updated();
+        }
+    };
+    ImGui::AlignTextToFramePadding();
+    ImGui::TextUnformatted("Priority is:"); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Unknown", &filter->wanted, static_cast<unsigned int>(Priority::Unknown))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Verbose", &filter->wanted, static_cast<unsigned int>(Priority::Verbose))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Debug", &filter->wanted, static_cast<unsigned int>(Priority::Debug))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Info", &filter->wanted, static_cast<unsigned int>(Priority::Info))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Warning", &filter->wanted, static_cast<unsigned int>(Priority::Warn))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Error", &filter->wanted, static_cast<unsigned int>(Priority::Error))); ImGui::SameLine();
+    update_if_needed(ImGui::CheckboxFlags("Fatal", &filter->wanted, static_cast<unsigned int>(Priority::Fatal)));
+}
+
+static inline void render_group_filter(GroupFilter* filter) {
+    int selected_type = static_cast<int>(filter->type);
+    if (ImGui::Combo("of these are true", &selected_type, "All\0Any\0One\0None\0")) {
+        filter->type = static_cast<GroupFilter::Type>(selected_type);
+    }
+
+    for (std::vector<std::unique_ptr<Filter>>::iterator it = filter->filters.begin(); it != filter->filters.end();) {
+        bool removal_requested = false;
+        render_filter(it->get(), nullptr, &removal_requested);
+        if (removal_requested) {
+            filter->filters.erase(it);
+            filter->updated();
+        } else {
+            it++;
+        }
+    }
+
+    std::string add_filter_id = std::string("addfilter_") + std::to_string(reinterpret_cast<size_t>(filter));
+    if (ImGui::Button("+ add filter")) {
+        ImGui::OpenPopup(add_filter_id.c_str());
+    }
+    if (ImGui::BeginPopup(add_filter_id.c_str())) {
+        std::unique_ptr<Filter> added_filter = render_add_filter_popup();
+        if (added_filter) {
+            filter->filters.push_back(std::move(added_filter));
+            filter->updated();
+        }
+        ImGui::EndPopup();
+    }
+}
+
+static inline std::unique_ptr<Filter> render_add_filter_popup() {
+    if (ImGui::Selectable("Buffer")) {
+        return std::make_unique<BufferFilter>(0);
+    } else if (ImGui::Selectable("User")) {
+        return std::make_unique<StringFilter>(FilterKey::User, "");
+    } else if (ImGui::Selectable("PID")) {
+        return std::make_unique<IntegerFilter>(FilterKey::PID, 0);
+    } else if (ImGui::Selectable("TID")) {
+        return std::make_unique<IntegerFilter>(FilterKey::TID, 0);
+    } else if (ImGui::Selectable("Priority")) {
+        return std::make_unique<PriorityFilter>(0);
+    } else if (ImGui::Selectable("Tag")) {
+        return std::make_unique<StringFilter>(FilterKey::Tag, "");
+    } else if (ImGui::Selectable("Message")) {
+        return std::make_unique<StringFilter>(FilterKey::Message, "");
+    } else if (ImGui::Selectable("Group of filters")) {
+        return std::make_unique<GroupFilter>(std::vector<std::unique_ptr<Filter>>(), GroupFilter::Type::All);
+    }
+
+    return std::unique_ptr<Filter>();
+}
+
+static void update_logcat_entries(const Filters& filters,
+        const std::vector<LogcatEntry>& logcat_entries, std::vector<size_t>& filtered_logcat_entry_offsets) {
+    filtered_logcat_entry_offsets.clear();
+    for (size_t i=0; i < logcat_entries.size(); i++) {
+        if (matches(filters, logcat_entries[i])) {
+            filtered_logcat_entry_offsets.push_back(i);
+        }
+    }
+}
+
+void filters_window(Filters& active_filters, Filters& inactive_filters,
+        const std::vector<LogcatEntry>& logcat_entries, std::vector<size_t>& filtered_logcat_entry_offsets,
+        bool* p_open) {
+    if (!ImGui::Begin("Filters", p_open)) {
+        ImGui::End();
+        return;
+    }
+
+    ImGui::TextUnformatted("You can use regex for strings by prepending \"regex:\"");
+
+    for (Filters::iterator it = inactive_filters.begin(); it != inactive_filters.end();) {
+        bool removal_requested = false;
+        render_filter(it->second.get(), &it->first, &removal_requested);
+        if (removal_requested) {
+            inactive_filters.erase(it);
+        } else {
+            it++;
+        }
+    }
+
+    if (ImGui::Button("+ add filter")) {
+        ImGui::OpenPopup("addfilter_root");
+    }
+    if (ImGui::BeginPopup("addfilter_root")) {
+        std::unique_ptr<Filter> added_filter = render_add_filter_popup();
+        if (added_filter) {
+            inactive_filters.push_back(std::make_pair("", std::move(added_filter)));
+        }
+        ImGui::EndPopup();
+    }
+
+    ImGui::Separator();
+    ImVec2 button_size(4 * ImGui::GetFontSize(), 0);
+    if (ImGui::Button("OK", button_size)) {
+        active_filters = std::move(inactive_filters);
+        update_logcat_entries(active_filters, logcat_entries, filtered_logcat_entry_offsets);
+        *p_open = false;
+    }
+    ImGui::SameLine();
+    if (ImGui::Button("Cancel", button_size)) {
+        *p_open = false;
+    }
+    ImGui::SameLine();
+    if (ImGui::Button("Apply", button_size)) {
+        copy_filters(active_filters, inactive_filters);
+        update_logcat_entries(active_filters, logcat_entries, filtered_logcat_entry_offsets);
+    }
+    ImGui::End();
+}
diff --git a/windows/filters.h b/windows/filters.h
new file mode 100644
index 0000000..2183699
--- /dev/null
+++ b/windows/filters.h
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <vector>
+
+#include "../logcat_entry.h"
+#include "../filters.h"
+
+void filters_window(Filters& active_filters, Filters& inactive_filters,
+        const std::vector<LogcatEntry>& logcat_entries, std::vector<size_t>& filtered_logcat_entry_offsets,
+        bool* p_open);
diff --git a/windows/main.cpp b/windows/main.cpp
index 9d35097..a3861c8 100644
--- a/windows/main.cpp
+++ b/windows/main.cpp
@@ -13,15 +13,15 @@ static std::string leftpad(std::string str, size_t characters) {
     return str;
 }
 
-static inline void main_scrolling_region(ImFont* monospace_font, std::vector<LogcatEntry>& filtered_logcat_entries) {
+static inline void main_scrolling_region(ImFont* monospace_font, std::vector<LogcatEntry>& logcat_entries, std::vector<size_t>& filtered_logcat_entry_offsets) {
     ImGui::PushFont(monospace_font);
     ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(0, 0));
 
     ImGuiListClipper clipper;
-    clipper.Begin(static_cast<int>(filtered_logcat_entries.size()));
+    clipper.Begin(static_cast<int>(filtered_logcat_entry_offsets.size()));
     while (clipper.Step()) {
         for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++) {
-            LogcatEntry* logcat_entry = &filtered_logcat_entries[static_cast<size_t>(i)];
+            LogcatEntry* logcat_entry = &logcat_entries[filtered_logcat_entry_offsets[static_cast<size_t>(i)]];
             char time_as_str[128] = {0};
             strftime(time_as_str, 127 * sizeof(char), "%c", localtime(&logcat_entry->time));
 
@@ -49,8 +49,11 @@ static inline void main_scrolling_region(ImFont* monospace_font, std::vector<Log
     }
 }
 
-void main_window(bool latest_log_entries_read, ImFont* monospace_font, std::vector<LogcatEntry>& filtered_logcat_entries,
-        const Config& active_config, Config& inactive_config, bool* show_settings_window, bool* show_logs_window, bool* run_event_loop) {
+void main_window(bool latest_log_entries_read, ImFont* monospace_font,
+        std::vector<LogcatEntry>& logcat_entries, std::vector<size_t>& filtered_logcat_entry_offsets,
+        const Config& active_config, Config& inactive_config,
+        const Filters& active_filters, Filters& inactive_filters,
+        bool* show_settings_window, bool* show_filters_window, bool* show_logs_window, bool* run_event_loop) {
     if (!ImGui::Begin("LogMeow", run_event_loop)) {
         ImGui::End();
         return;
@@ -61,6 +64,12 @@ void main_window(bool latest_log_entries_read, ImFont* monospace_font, std::vect
         *show_settings_window = true;
     }
 
+    ImGui::SameLine();
+    if (ImGui::Button("Filters") && !*show_filters_window) {
+        copy_filters(inactive_filters, active_filters);
+        *show_filters_window = true;
+    }
+
     ImGui::SameLine();
     if (!latest_log_entries_read) {
         ImGui::PushStyleColor(ImGuiCol_Button, (ImVec4)ImColor::HSV(0.0f, 0.6f, 0.6f));
@@ -79,7 +88,7 @@ void main_window(bool latest_log_entries_read, ImFont* monospace_font, std::vect
     // and [SECTION] Example App: Long Text / ShowExampleAppLongText()
     // and [SECTION] Example App: Debug Log / ShowExampleAppLog()
     if (ImGui::BeginChild("ScrollingRegion", ImVec2(0, 0), false, ImGuiWindowFlags_HorizontalScrollbar)) {
-        main_scrolling_region(monospace_font, filtered_logcat_entries);
+        main_scrolling_region(monospace_font, logcat_entries, filtered_logcat_entry_offsets);
     }
     ImGui::EndChild();
     ImGui::End();
diff --git a/windows/main.h b/windows/main.h
index 1939e11..18f168f 100644
--- a/windows/main.h
+++ b/windows/main.h
@@ -4,7 +4,11 @@
 #include <vector>
 
 #include "../config.h"
+#include "../filters.h"
 #include "../logcat_entry.h"
 
-void main_window(bool latest_log_entries_read, ImFont* monospace_font, std::vector<LogcatEntry>& filtered_logcat_entries,
-        const Config& active_config, Config& inactive_config, bool* show_settings_window, bool* show_logs_window, bool* run_event_loop);
+void main_window(bool latest_log_entries_read, ImFont* monospace_font,
+        std::vector<LogcatEntry>& logcat_entries, std::vector<size_t>& filtered_logcat_entry_offsets,
+        const Config& active_config, Config& inactive_config,
+        const Filters& active_filters, Filters& inactive_filters,
+        bool* show_settings_window, bool* show_filters_window, bool* show_logs_window, bool* run_event_loop);
diff --git a/windows/settings.cpp b/windows/settings.cpp
index f0baa44..c1f6d9e 100644
--- a/windows/settings.cpp
+++ b/windows/settings.cpp
@@ -14,15 +14,12 @@ static void write_config_and_update_structures(const Config& config) {
 }
 
 void settings_window(Config& active_config, Config& inactive_config, bool* p_open) {
-    ImGuiWindowFlags flags = active_config != inactive_config
-        ? ImGuiWindowFlags_UnsavedDocument
-        : 0;
-    if (!ImGui::Begin("Settings", p_open, flags)) {
+    if (!ImGui::Begin("Settings", p_open)) {
         ImGui::End();
         return;
     }
     // TODO actually have process control
-    ImGui::Text("Logcat command only takes effect when logcat is not running");
+    ImGui::TextUnformatted("Logcat command only takes effect when logcat is not running");
     ImGui::InputTextWithHint("Logcat command", "adb logcat -Dv 'threadtime UTC epoch usec uid'", &inactive_config.logcat_command);
 
     ImGui::Text("Font sizes only take effect when LogMeow is restarted");
@@ -34,7 +31,7 @@ void settings_window(Config& active_config, Config& inactive_config, bool* p_ope
     ImGui::Separator();
     ImVec2 button_size(4 * ImGui::GetFontSize(), 0);
     if (ImGui::Button("OK", button_size)) {
-        active_config = inactive_config;
+        active_config = std::move(inactive_config);
         write_config_and_update_structures(active_config);
         *p_open = false;
     }