I have an ActiveX control that fits in an IE browser container. The control creates another dialog box with the WS_POPUP and WS_LAYERED properties enabled to be able to use the SetLayeredWindowAttributes (...) function to achieve color-coded transparency and alpha blending on top of the control.
Because the WS_LAYERED property cannot be used in conjunction with the WS_CHILD property, window visibility control is not automatic. I need to determine when the ActiveX control is no longer displayed (i.e., since the browser tab has been changed or minimized), so I can change the visibility of the overlay window.
I tried using some of the existing window messages (WM_) to detect this change, but did not see them work when the IE browser tab changes. Does anyone know a better way to capture when visibility changes happen?
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