(svn r12018) -Fix(FS#1721,r9563): Restore initial intent on the invisible tree while transparent building patch setting

src/transparency_gui.cpp

@@ -7,6 +7,7 @@
 #include "variables.h"
 #include "transparency.h"
 #include "sound_func.h"
+#include "settings_type.h"
 
 #include "table/sprites.h"
 #include "table/strings.h"
@@ -37,6 +38,11 @@ static void TransparencyToolbWndProc(Window *w, WindowEvent *e)
 			for (uint i = TTW_WIDGET_SIGNS; i < TTW_WIDGET_END; i++) {
 				w->SetWidgetLoweredState(i, IsTransparencySet((TransparencyOption)(i - TTW_WIDGET_SIGNS)));
 			}
+
+			/* Disabling the trees button allows to make it very evident that it has no effect
+			 * upon current situation */
+			w->SetWidgetDisabledState(TTW_WIDGET_TREES, _patches.invisible_trees && IsTransparencySet(TO_HOUSES));
+
 			DrawWindowWidgets(w);
 			break;