Resolves: rhbz#855541 XIOError handler multithread woes

We have two threads using X, on an XIOError both
threads call their XIOError handlers and two
calls to exit trample all over eachother.

Change-Id: I20defc6f84cc6ea2372a0d6c979e8078fe920a88

vcl/unx/generic/app/saldata.cxx

@@ -322,6 +322,12 @@ int X11SalData::XErrorHdl( Display *pDisplay, XErrorEvent *pEvent )
 
 int X11SalData::XIOErrorHdl( Display * )
 {
+    if (::osl::Thread::getCurrentIdentifier() != Application::GetMainThreadIdentifier())
+    {
+        pthread_exit(NULL);
+        return 0;
+    }
+
     /*  #106197# hack: until a real shutdown procedure exists
      *  _exit ASAP
      */

vcl/unx/gtk/app/gtkdata.cxx

@@ -526,6 +526,18 @@ GtkData::GtkData( SalInstance *pInstance )
     m_aDispatchCondition = osl_createCondition();
 }
 
+XIOErrorHandler aOrigXIOErrorHandler = NULL;
+
+int XIOErrorHdl(Display *pDisplay)
+{
+    if (::osl::Thread::getCurrentIdentifier() != Application::GetMainThreadIdentifier())
+    {
+        pthread_exit(NULL);
+        return 0;
+    }
+    return aOrigXIOErrorHandler ? aOrigXIOErrorHandler(pDisplay) : 0;
+}
+
 GtkData::~GtkData()
 {
     Yield( true, true );
@@ -545,6 +557,7 @@ GtkData::~GtkData()
     osl_destroyCondition( m_aDispatchCondition );
     osl_releaseMutex( m_aDispatchMutex );
     osl_destroyMutex( m_aDispatchMutex );
+    XSetIOErrorHandler(aOrigXIOErrorHandler);
 }
 
 void GtkData::Dispose()
@@ -664,6 +677,7 @@ void GtkData::Init()
     // init gtk/gdk
     gtk_init_check( &nParams, &pCmdLineAry );
     gdk_error_trap_push();
+    aOrigXIOErrorHandler = XSetIOErrorHandler(XIOErrorHdl);
 
     for (i = 0; i < nParams; i++ )
         g_free( pCmdLineAry[i] );