gui2/tcustom_tod: Fix window disappearing after RGB slider updates

Since there is no longer a direct way to mark the whole window as dirty
for some reason, we need to both invalidate the layout and force it to
be redrawn in its entirety.

src/gui/dialogs/editor/custom_tod.cpp

@@ -204,6 +204,9 @@ void tcustom_tod::update_tod_display(twindow& window)
 		// redraw tiles
 		display_->draw();
 	}
+
+	window.invalidate_layout();
+	window.draw();
 }
 
 void tcustom_tod::update_lawful_bonus(twindow& window)