Add hotkey categories filter to preferences

This allows the user to filter out certain types of hotkeys,
making it easier to locate a specific hotkey.

data/gui/window/preferences.cfg

@@ -184,6 +184,11 @@
 			fixed_width = "true"
 		[/linked_group]
 
+		[linked_group]
+			id = "hotkeys_categories"
+			fixed_width = true
+		[/linked_group]
+
 		[tooltip]
 			id = "tooltip"
 		[/tooltip]

data/gui/window/preferences/02_hotkeys.cfg

@@ -1,9 +1,56 @@
 #textdomain wesnoth-lib
 ###
-### Preferences dialog, Advanced page
+### Preferences dialog, Hotkeys page
 ###
 
 [layer]
+	[row]
+		grow_factor = 0
+
+		[column]
+			horizontal_grow = true
+			vertical_alignment = "top"
+			border = "all"
+			border_size = 5
+
+			[grid_listbox]
+				id = "list_categories"
+				definition = "default"
+				has_minimum = true
+				has_maximum = false
+				[list_definition]
+					[row]
+						[column]
+							[toggle_panel]
+								definition = "default"
+								linked_group = "hotkeys_categories"
+								[grid]
+									[row]
+										#{_GUI_INFO_TAB_PADDING}
+
+										[column]
+											grow_factor = 1
+											border = all
+											border_size = 5
+
+											[label]
+												id = "cat_label"
+												definition = "default_tiny"
+												wrap = true
+											[/label]
+
+										[/column]
+
+										#{_GUI_INFO_TAB_PADDING}
+									[/row]
+								[/grid]
+							[/toggle_panel]
+						[/column]
+					[/row]
+				[/list_definition]
+			[/grid_listbox]
+		[/column]
+	[/row]
 
 	[row]
 		grow_factor = 1

src/gui/dialogs/preferences_dialog.cpp

@@ -848,10 +848,57 @@ void tpreferences::initialize_members(twindow& window)
 
 	row_data.clear();
 
+	tlistbox& hotkey_categories = find_widget<tlistbox>(&window, "list_categories", false);
+
+	const std::string cat_names[] = {
+		// TODO: This list needs to be synchronized with the hotkey::HOTKEY_CATEGORY enum
+		// Find some way to do that automatically
+		_("General"),
+		_("Saved Games"),
+		_("Map Commands"),
+		_("Unit Commands"),
+		_("Player Chat"),
+		_("Replay Control"),
+		_("Planning Mode"),
+		_("Scenario Editor"),
+		_("Editor Palettes"),
+		_("Editor Tools"),
+		_("Editor Clipboard"),
+		_("Editor Selection"),
+		_("Debug Commands"),
+		_("Custom WML Commands"),
+		// HKCAT_PLACEHOLDER intentionally excluded (it shouldn't have any anyway)
+	};
+
+	for(int i = 0; i <= hotkey::HKCAT_PLACEHOLDER; i++) {
+		row_data["cat_label"]["label"] = cat_names[i];
+		hotkey_categories.add_row(row_data);
+		hotkey_categories.select_row(hotkey_categories.get_item_count() - 1);
+	}
+
 	setup_hotkey_list(window);
 
 	tlistbox& hotkey_list = find_widget<tlistbox>(&window, "list_hotkeys", false);
 
+	hotkey_categories.set_callback_item_change([&hotkey_list, &hotkey_categories](size_t i) {
+		if(i >= hotkey::HKCAT_PLACEHOLDER) {
+			return;
+		}
+		hotkey::HOTKEY_CATEGORY cat = hotkey::HOTKEY_CATEGORY(i);
+		// For listboxes that allow multiple selection, get_selected_row() returns the most
+		// recently selected row. Thus, if it returns i, this row was just selected.
+		// Otherwise, it must have been deselected.
+		bool show = hotkey_categories.get_selected_row() == int(i);
+		std::vector<bool> mask = hotkey_list.get_rows_shown();
+		auto hotkeys = hotkey::get_hotkey_commands();
+		for(size_t j = 0; j < hotkeys.size(); j++) {
+			if(hotkeys[j].category == cat) {
+				mask[j] = show;
+			}
+		}
+		hotkey_list.set_row_shown(mask);
+	});
+
 	// Action column
 	hotkey_list.register_sorting_option(0, [this](const int i) { return visible_hotkeys_[i]->description.str(); });
 

src/gui/widgets/listbox.cpp

@@ -214,6 +214,15 @@ void tlistbox::set_row_shown(const std::vector<bool>& shown)
 	}
 }
 
+std::vector<bool> tlistbox::get_rows_shown() const
+{
+	std::vector<bool> shown;
+	for(size_t i = 0; i < get_item_count(); i++) {
+		shown.push_back(generator_->get_item_shown(i));
+	}
+	return shown;
+}
+
 const tgrid* tlistbox::get_row_grid(const unsigned row) const
 {
 	assert(generator_);

src/gui/widgets/listbox.hpp

@@ -142,6 +142,13 @@ class tlistbox : public tscrollbar_container
 	 */
 	void set_row_shown(const std::vector<bool>& shown);
 
+	/**
+	 * Returns a list of visible rows
+	 *
+	 * @returns                   A mask indicating which rows are visible
+	 */
+	std::vector<bool> get_rows_shown() const;
+
 	/**
 	 * Returns the grid of the wanted row.
 	 *