patch 9.0.0454: incorrect color for modeless selection with GTK

Problem:    Incorrect color for modeless selection with GTK.
Solution:   Use simple inversion instead of XOR. (closes #11111)

Author: Your Name

src/gui_gtk_x11.c

@@ -6261,7 +6261,7 @@ gui_mch_invert_rectangle(int r, int c, int nr, int nc)
     };
     cairo_t * const cr = cairo_create(gui.surface);
 
-    set_cairo_source_rgba_from_color(cr, gui.norm_pixel ^ gui.back_pixel);
+    cairo_set_source_rgba(cr, 1.0, 1.0, 1.0, 1.0);
 # if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1,9,2)
     cairo_set_operator(cr, CAIRO_OPERATOR_DIFFERENCE);
 # else
@@ -6281,13 +6281,9 @@ gui_mch_invert_rectangle(int r, int c, int nr, int nc)
     if (gui.drawarea->window == NULL)
 	return;
 
-    values.foreground.pixel = gui.norm_pixel ^ gui.back_pixel;
-    values.background.pixel = gui.norm_pixel ^ gui.back_pixel;
-    values.function = GDK_XOR;
+    values.function = GDK_INVERT;
     invert_gc = gdk_gc_new_with_values(gui.drawarea->window,
 				       &values,
-				       GDK_GC_FOREGROUND |
-				       GDK_GC_BACKGROUND |
 				       GDK_GC_FUNCTION);
     gdk_gc_set_exposures(invert_gc, gui.visibility !=
 						   GDK_VISIBILITY_UNOBSCURED);

src/version.c

@@ -703,6 +703,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    454,
 /**/
     453,
 /**/