It appears that the spinner on the GTK2 version of wx.TimeCtrl is
limited to the time initially set in the control. When the time is at
that value or if decrementing the cursor field (hours, minutes, etc)
would result in a time earlier than the time, the decrement spinner
button is disabled. The down-arrow key will still decrement the time.
Under Windows, this doesn't seem to be an issue.
This behavior can be seen in the wxPython demo.
Mark