diff --git a/src/graph_gui.cpp b/src/graph_gui.cpp
--- a/src/graph_gui.cpp
+++ b/src/graph_gui.cpp
@@ -56,7 +56,7 @@ struct GraphLegendWindow : Window {
 		}
 	}
 
-	void DrawWidget(const Rect &r, int widget) const override
+	void DrawWidget(const Rect &r, WidgetID widget) const override
 	{
 		if (!IsInsideMM(widget, WID_GL_FIRST_COMPANY, MAX_COMPANIES + WID_GL_FIRST_COMPANY)) return;
 
@@ -76,7 +76,7 @@ struct GraphLegendWindow : Window {
 		DrawString(tr.left, tr.right, CenterBounds(tr.top, tr.bottom, GetCharacterHeight(FS_NORMAL)), STR_COMPANY_NAME_COMPANY_NUM, HasBit(_legend_excluded_companies, cid) ? TC_BLACK : TC_WHITE);
 	}
 
-	void OnClick([[maybe_unused]] Point pt, int widget, [[maybe_unused]] int click_count) override
+	void OnClick([[maybe_unused]] Point pt, WidgetID widget, [[maybe_unused]] int click_count) override
 	{
 		if (!IsInsideMM(widget, WID_GL_FIRST_COMPANY, MAX_COMPANIES + WID_GL_FIRST_COMPANY)) return;
 
@@ -115,7 +115,7 @@ static NWidgetBase *MakeNWidgetCompanyLi
 	vert->SetPadding(2, 2, 2, 2);
 	uint sprite_height = GetSpriteSize(SPR_COMPANY_ICON, nullptr, ZOOM_LVL_OUT_4X).height;
 
-	for (int widnum = WID_GL_FIRST_COMPANY; widnum <= WID_GL_LAST_COMPANY; widnum++) {
+	for (WidgetID widnum = WID_GL_FIRST_COMPANY; widnum <= WID_GL_LAST_COMPANY; widnum++) {
 		NWidgetBackground *panel = new NWidgetBackground(WWT_PANEL, COLOUR_BROWN, widnum);
 		panel->SetMinimalSize(246, sprite_height + WidgetDimensions::unscaled.framerect.Vertical());
 		panel->SetMinimalTextLines(1, WidgetDimensions::unscaled.framerect.Vertical(), FS_NORMAL);
@@ -191,7 +191,7 @@ protected:
 	uint16_t x_values_start;
 	uint16_t x_values_increment;
 
-	int graph_widget;
+	WidgetID graph_widget;
 	StringID format_str_y_axis;
 	byte colours[GRAPH_MAX_DATASETS];
 	OverflowSafeInt64 cost[GRAPH_MAX_DATASETS][GRAPH_NUM_MONTHS]; ///< Stored costs for the last #GRAPH_NUM_MONTHS months
@@ -471,7 +471,7 @@ protected:
 	}
 
 
-	BaseGraphWindow(WindowDesc *desc, int widget, StringID format_str_y_axis) :
+	BaseGraphWindow(WindowDesc *desc, WidgetID widget, StringID format_str_y_axis) :
 			Window(desc),
 			format_str_y_axis(format_str_y_axis)
 	{
@@ -489,7 +489,7 @@ protected:
 	}
 
 public:
-	void UpdateWidgetSize(int widget, Dimension *size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension *fill, [[maybe_unused]] Dimension *resize) override
+	void UpdateWidgetSize(WidgetID widget, Dimension *size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension *fill, [[maybe_unused]] Dimension *resize) override
 	{
 		if (widget != this->graph_widget) return;
 
@@ -525,7 +525,7 @@ public:
 		size->height = std::max<uint>(size->height, size->width / 3);
 	}
 
-	void DrawWidget(const Rect &r, int widget) const override
+	void DrawWidget(const Rect &r, WidgetID widget) const override
 	{
 		if (widget != this->graph_widget) return;
 
@@ -537,7 +537,7 @@ public:
 		return INVALID_DATAPOINT;
 	}
 
-	void OnClick([[maybe_unused]] Point pt, int widget, [[maybe_unused]] int click_count) override
+	void OnClick([[maybe_unused]] Point pt, WidgetID widget, [[maybe_unused]] int click_count) override
 	{
 		/* Clicked on legend? */
 		if (widget == WID_CV_KEY_BUTTON) ShowGraphLegend();
@@ -778,7 +778,7 @@ struct PerformanceHistoryGraphWindow : B
 		return c->old_economy[j].performance_history;
 	}
 
-	void OnClick([[maybe_unused]] Point pt, int widget, [[maybe_unused]] int click_count) override
+	void OnClick([[maybe_unused]] Point pt, WidgetID widget, [[maybe_unused]] int click_count) override
 	{
 		if (widget == WID_PHG_DETAILED_PERFORMANCE) ShowPerformanceRatingDetail();
 		this->BaseGraphWindow::OnClick(pt, widget, click_count);
@@ -912,7 +912,7 @@ struct PaymentRatesGraphWindow : BaseGra
 		}
 	}
 
-	void UpdateWidgetSize(int widget, Dimension *size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension *fill, [[maybe_unused]] Dimension *resize) override
+	void UpdateWidgetSize(WidgetID widget, Dimension *size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension *fill, [[maybe_unused]] Dimension *resize) override
 	{
 		if (widget != WID_CPR_MATRIX) {
 			BaseGraphWindow::UpdateWidgetSize(widget, size, padding, fill, resize);
@@ -936,7 +936,7 @@ struct PaymentRatesGraphWindow : BaseGra
 		resize->height = this->line_height;
 	}
 
-	void DrawWidget(const Rect &r, int widget) const override
+	void DrawWidget(const Rect &r, WidgetID widget) const override
 	{
 		if (widget != WID_CPR_MATRIX) {
 			BaseGraphWindow::DrawWidget(r, widget);
@@ -973,7 +973,7 @@ struct PaymentRatesGraphWindow : BaseGra
 		}
 	}
 
-	void OnClick([[maybe_unused]] Point pt, int widget, [[maybe_unused]] int click_count) override
+	void OnClick([[maybe_unused]] Point pt, WidgetID widget, [[maybe_unused]] int click_count) override
 	{
 		switch (widget) {
 			case WID_CPR_ENABLE_CARGOES:
@@ -1140,7 +1140,7 @@ struct PerformanceRatingDetailWindow : W
 	uint score_detail_left;
 	uint score_detail_right;
 
-	void UpdateWidgetSize(int widget, Dimension *size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension *fill, [[maybe_unused]] Dimension *resize) override
+	void UpdateWidgetSize(WidgetID widget, Dimension *size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension *fill, [[maybe_unused]] Dimension *resize) override
 	{
 		switch (widget) {
 			case WID_PRD_SCORE_FIRST:
@@ -1198,7 +1198,7 @@ struct PerformanceRatingDetailWindow : W
 		}
 	}
 
-	void DrawWidget(const Rect &r, int widget) const override
+	void DrawWidget(const Rect &r, WidgetID widget) const override
 	{
 		/* No need to draw when there's nothing to draw */
 		if (this->company == INVALID_COMPANY) return;
@@ -1276,7 +1276,7 @@ struct PerformanceRatingDetailWindow : W
 		}
 	}
 
-	void OnClick([[maybe_unused]] Point pt, int widget, [[maybe_unused]] int click_count) override
+	void OnClick([[maybe_unused]] Point pt, WidgetID widget, [[maybe_unused]] int click_count) override
 	{
 		/* Check which button is clicked */
 		if (IsInsideMM(widget, WID_PRD_COMPANY_FIRST, WID_PRD_COMPANY_LAST + 1)) {
@@ -1355,7 +1355,7 @@ static NWidgetBase *MakePerformanceDetai
 	static_assert(lengthof(performance_tips) == SCORE_END - SCORE_BEGIN);
 
 	NWidgetVertical *vert = new NWidgetVertical(NC_EQUALSIZE);
-	for (int widnum = WID_PRD_SCORE_FIRST; widnum <= WID_PRD_SCORE_LAST; widnum++) {
+	for (WidgetID widnum = WID_PRD_SCORE_FIRST; widnum <= WID_PRD_SCORE_LAST; widnum++) {
 		NWidgetBackground *panel = new NWidgetBackground(WWT_PANEL, COLOUR_BROWN, widnum);
 		panel->SetFill(1, 1);
 		panel->SetDataTip(0x0, performance_tips[widnum - WID_PRD_SCORE_FIRST]);