Fix crash due to logging bug in the event sample

The gestures frame created its own log target and deleted
the previous one but did not restore it when being closed.

This left the current log target invalid which led to a crash
when calling any wxLog*() function after gestures frame was closed.

Fix this by restoring the previous log target when gestures frame
is closed.

Closes #23767.

See #23881.

samples/event/gestures.cpp

@@ -23,7 +23,7 @@ MyGestureFrame::MyGestureFrame()
     SetSizeHints(wxMin(800,dsplySz.GetWidth()), wxMin(600,dsplySz.GetHeight()));
 
     // Log to the text control
-    delete wxLog::SetActiveTarget(new wxLogTextCtrl(m_logText));
+    m_logOld = wxLog::SetActiveTarget(new wxLogTextCtrl(m_logText));
 
     // Bind all gestures to the same event handler, which must run before
     // the other handlers, to clear the log window
@@ -64,6 +64,7 @@ MyGesturePanel::MyGesturePanel(MyGestureFrame *parent)
 
 void MyGestureFrame::OnQuit(wxCloseEvent& WXUNUSED(event))
 {
+    delete wxLog::SetActiveTarget(m_logOld);
     Destroy();
 }
 

samples/event/gestures.h

@@ -12,6 +12,7 @@ public:
     void OnQuit(wxCloseEvent& event);
 
 private:
+    wxLog *m_logOld;
     wxTextCtrl *m_logText;
 };