I find that APL+Win "value tips" blink on and off repeatedly when certain mouse pointer schemes are in effect.
Go to Control Panel, Mouse Properties, "Pointers" tab, and set the "Scheme".
When I use the "Windows Standard (large)" or "Windows Standard (extra large)" mouse pointer scheme, value tips blink; if I go back to the "Windows Default" scheme, the value tips stop blinking. This is with APL version 5.2, although I think it has been happening since version 3.6.
It would be nice if this could be fixed. Some of us geezers like those larger mouse pointers...