Prevent crashes on macOS caused by calling TheWorldHasChanged from inside [NSView drawRect]

1 files changed, 14 insertions, 1 deletions

diff --git a/generic/tkFont.c b/generic/tkFont.c
index 86fdd87..156ebf3 100644
--- a/generic/tkFont.c
+++ b/generic/tkFont.c
@@ -13,7 +13,9 @@
 
 #include "tkInt.h"
 #include "tkFont.h"
-
+#if defined(MAC_OSX_TK)
+#include "tkMacOSXInt.h"
+#endif
 /*
  * The following structure is used to keep track of all the fonts that exist
  * in the current application. It must be stored in the TkMainInfo for the
@@ -872,7 +874,18 @@ TheWorldHasChanged(
     ClientData clientData)	/* Info about application's fonts. */
 {
     TkFontInfo *fiPtr = clientData;
+#if defined(MAC_OSX_TK)
 
+    /*
+     * On macOS it is catastrophic to recompute all widgets while the
+     * [NSView drawRect] method is drawing. The best that we can do in
+     * that situation is to abort the recomputation and hope for the best.
+     */
+    
+    if (TkpAppIsDrawing()) {
+	return;
+    }
+#endif
     fiPtr->updatePending = 0;
     RecomputeWidgets(fiPtr->mainPtr->winPtr);
 }