added wxWS_EX_TRANSIENT, added code for handling it and fixed wxLogGeneric

to avoid crashes related to creating the log dialog as child of a window which
is destroyed before it is


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@12781 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/defs.h

@@ -784,6 +784,12 @@ enum wxBorder
 // flag on by default.
 #define wxWS_EX_BLOCK_EVENTS            0x00000002
 
+// don't use this window as an implicit parent for the other windows: this must
+// be used with transient windows as otherwise there is the risk of creating a
+// dialog/frame with this window as a parent which would lead to a crash if the
+// parent is destroyed before the child
+#define wxWS_EX_TRANSIENT               0x00000004
+
 /*
  * wxFrame/wxDialog style flags
  */