Remove visible lag on displaying first picture of background

openlp/core/ui/maindisplay.py

@@ -183,6 +183,9 @@ class MainDisplay(DisplayWidget):
             The slide text to be displayed
         """
         log.debug(u'text')
+        # Wait for the webview to update before displayiong text.
+        while not self.loaded:
+            Receiver.send_message(u'openlp_process_events')
         self.frame.evaluateJavaScript(u'show_text("%s")' % \
             slide.replace(u'\\', u'\\\\').replace(u'\"', u'\\\"'))
         return self.preview()