git-gui: Correct is_MacOSX platform test.

diff --git a/git-gui b/git-gui
index 3e53fbd623f14446de6aabb79614ce34ef6e0cfe..afd9ac026e79cce4811de0cb4fa9b7c6d6bc23f6 100755 (executable)
--- a/git-gui
+++ b/git-gui
@@ -1716,9 +1716,7 @@ unset filemask i
 
 proc is_MacOSX {} {
        global tcl_platform tk_library
-       if {$tcl_platform(platform) eq {unix}
-               && $tcl_platform(os) eq {Darwin}
-               && [string match /Library/Frameworks/* $tk_library]} {
+       if {[tk windowingsystem] eq {aqua}} {
                return 1
        }
        return 0