Fix #13645: "Follow vehicle" button not raised when following stopped. (#13746)

src/viewport.cpp

@@ -94,6 +94,8 @@
 #include <forward_list>
 #include <stack>
 
+#include "widgets/vehicle_widget.h"
+
 #include "table/strings.h"
 #include "table/string_colours.h"
 
@@ -2530,7 +2532,7 @@ bool ScrollWindowTo(int x, int y, int z, Window *w, bool instant)
 	}
 
 	Point pt = MapXYZToViewport(w->viewport, x, y, z);
-	w->viewport->follow_vehicle = VehicleID::Invalid();
+	w->viewport->CancelFollow(*w);
 
 	if (w->viewport->dest_scrollpos_x == pt.x && w->viewport->dest_scrollpos_y == pt.y) return false;
 
@@ -3717,3 +3719,21 @@ void SetViewportCatchmentTown(const Town *t, bool sel)
 	}
 	if (_viewport_highlight_town != nullptr) SetWindowDirty(WC_TOWN_VIEW, _viewport_highlight_town->index);
 }
+
+/**
+ * Cancel viewport vehicle following, and raise follow location widget if needed.
+ * @param viewport_window Window of this viewport.
+ */
+void ViewportData::CancelFollow(const Window &viewport_window)
+{
+	if (this->follow_vehicle == VehicleID::Invalid()) return;
+
+	if (viewport_window.window_class == WC_MAIN_WINDOW) {
+		/* We're cancelling follow in the main viewport, so we need to check for a vehicle view window
+		 * to raise the location follow widget. */
+		Window *vehicle_window = FindWindowById(WC_VEHICLE_VIEW, this->follow_vehicle);
+		if (vehicle_window != nullptr) vehicle_window->RaiseWidgetWhenLowered(WID_VV_LOCATION);
+	}
+
+	this->follow_vehicle = VehicleID::Invalid();
+}