[dia] Do not crash if sheet dialog creation fails

[Hans Breuer <hans src gnome org>]

commit 139e97ad23f69d1303899a673caeba1800de7e95
Author: Hans Breuer <hans breuer org>
Date:   Fri Oct 23 13:16:40 2009 +0200

    Do not crash if sheet dialog creation fails
    
    The sheet dialog creation is not crucial enough to make the whole
    program fail. Also it depends on an external gbuilder file
    (sheets-dialog.xml) which may get broken independent of the build.

 app/sheets.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/app/sheets.c b/app/sheets.c
index 5e1e02b..9a286e0 100644
--- a/app/sheets.c
+++ b/app/sheets.c
@@ -220,6 +220,11 @@ sheets_dialog_create(void)
   if (sheets_dialog == NULL)
   {
     sheets_dialog = create_sheets_main_dialog();
+    if (!sheets_dialog) {
+      /* don not let a broken builder file crash Dia */
+      g_warning("SheetDialog creation failed");
+      return FALSE;
+    }
     /* Make sure to null our pointer when destroyed */
     g_signal_connect (GTK_OBJECT (sheets_dialog), "destroy",
 		      G_CALLBACK (gtk_widget_destroyed),