wxGUI/forms: fix options range for negative values

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@59346 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/gui_core/forms.py

@@ -1024,7 +1024,7 @@ class CmdPanel(wx.Panel):
 
                             # for multiple integers use textctrl instead of spinsctrl
                             try:
-                                minValue, maxValue = map(int, valuelist[0].split('-'))
+                                minValue, maxValue = map(int, valuelist[0].rsplit('-', 1))
                             except ValueError:
                                 minValue = -1e6
                                 maxValue = 1e6