def on_click(self):
try:
ll = float(self.fields['Length_Limit'].widget.text())
bw = float(self.fields['BandWidth'].widget.text())
dilate = ll * bw
except ValueError:
dilate = 0
self.grid_dialog.set_grid(
Grid.make_from_catalogue(self.catalogue, 1, dilate))
if self.grid_dialog.exec_():
self.grid = self.grid_dialog.get_grid()
