wxgui: g.region: can't reset `rows=' nor `cols='

[msieczka]

1. Run g.region from wxgui.

2. `Resolution' tab.

3. Change the `Number of rows in region'.

4. "Oops, I wanted to edit the resolution instead."

5. Edit the `Grid resolution 2D (...)' field as you intended too.

6. You can't reset `rows=' in the GUI now.