When trying out IceWM at first I thought it was not working at all. From a reboot, whenever the 'Start' menu button was clicked the only response was to display the window list as if that button had been clicked. Indeed whichever button was operated the window list. was shown.
By sheer chance, the machine was rebooted without the noicons bootcode and Wbar was displayed. Starting any of the apps via Wbar seems to kick IceWM into life as it then begins to work as expected.
IceWM was removed along with configuration files I could find and FLWM reinstated which worked correctly. Reinstalling IceWM, the symptoms returned.
This is repeatable with the preferences file created by the default install, and also after the preferences file has been has been copied to the home dir and edited.