Do not process idle events before withdrawing a window.

1 files changed, 11 insertions, 1 deletions

diff --git a/macosx/tkMacOSXWm.c b/macosx/tkMacOSXWm.c
index e039072..a4bc102 100644
--- a/macosx/tkMacOSXWm.c
+++ b/macosx/tkMacOSXWm.c
@@ -6447,9 +6447,19 @@ TkpWmSetState(
     macWin = TkMacOSXGetNSWindowForDrawable(winPtr->window);
 
     /*
-     * Make sure windows are updated before the state change.
+     * Make sure windows are updated before the state change.  As an exception,
+     * do not do process idle tasks before withdrawing a window.  The purpose of
+     * this is to support the common paradigm of immediately withdrawing the root
+     * window.  Processing idle tasks before changing the state causes the root
+     * to briefly flash on the screen, which users of this paradigm find annoying.
+     * Not processing the events does not guarantee that the window will not appear
+     * but it makes it more likely. 
      */
 
+    if (state != WithdrawnState) {
+	while (Tcl_DoOneEvent(TCL_IDLE_EVENTS)) {};
+    }
+
     while (Tcl_DoOneEvent(TCL_IDLE_EVENTS)) {};
 
     if (state == WithdrawnState) {