Comment 1 for bug 662360

-Could you confirm that you actually see the button change from run to stop when you press run/F8? In fr0st 1.2, the buttons for run/stop were merged into 1, so that may be causing trouble.

-Does this only happen with scripts that contain infinite loops, like default.py? Can you try some of the scripts that are put into favorites by default, such as reframe and xform_heat_map?

-Does the app stay responsive while the script is running (e.g. tooltips popping up, being able to change tabs)?

-Finally, what's your wxpython version?
    python -c "import wx; print wx.version()"