Blurs UI while processing

Before the processing of a query starts, it will blur the UI.

This gives feedback to the user that something is happening, and is
simple to implement because I am too lazy to move the processing in
a separate thread.

CHANGELOG

@@ -1,6 +1,7 @@
 2.2
 - Added again make install target
 - Ctrl+C in the terminal will terminate the GUI
+- Blurs UI while processing
 
 2.1
 - Introduced sessions; GUI loads the same relations of the previous time

relational_gui/guihandler.py

@@ -133,6 +133,12 @@ class relForm(QtWidgets.QMainWindow):
         self.showRelation(self.selectedRelation)
 
     def execute(self):
+
+        blur = QtWidgets.QGraphicsBlurEffect()
+        self.setGraphicsEffect(blur)
+        QtCore.QCoreApplication.processEvents()
+
+        try:
             '''Executes the query'''
             if self.multiline:
                 return self._run_multiline()
@@ -161,6 +167,9 @@ class relForm(QtWidgets.QMainWindow):
             self.qcounter += 1
             # Sets the result relation name to none
             self.ui.txtResult.setText(u"_last%d" % self.qcounter)
+        finally:
+            blur.setBlurRadius(0)
+
 
     def showRelation(self, rel):
         '''Shows the selected relation into the table'''