Revert "Clear pixmap to black before starting to draw"

src/x.c

@@ -706,7 +706,6 @@ void x_draw_decoration(Con *con) {
 
     x_draw_decoration_after_title(con, p);
 copy_pixmaps:
-    draw_util_clear_surface(&(con->frame_buffer), (color_t){.red = 0.0, .green = 0.0, .blue = 0.0});
     draw_util_copy_surface(&(con->frame_buffer), &(con->frame), 0, 0, 0, 0, con->rect.width, con->rect.height);
 }