Flickering with ComboBox


Hi all,

I’ve got a problem with a ComboBox which is inside a custom GUI component in my audio plugin editor. Symptoms are that the combo box sometimes flickers as it is opened. Sometimes it opens normally, other times it flicks open and then shuts by itself and other times it flicks on, off then on again rapidly.

Am in Win7 x64 and using the latest tip. Have tried with an earlier tip to no avail. Anyone else seeing a similar problem?


Presumably this is the popup menu that’s flickering, and not the combo box itself? The host could be messing about with window positioning and mouse-capture - have you tried it in different hosts?


Yes, it’s the popup and not the box itself Jules. Happens in the Juce plugin host and Reaper - I can try it in Cubase and StudioOne on another PC tomorrow if it would help.


Just a better description of what exactly is going on would be useful. Is the menu being shown and then hidden and then shown again, or is the window just being jiggled forwards/backwards in the z-order…?


Looks like the former to me. Maybe a short video helps: http://img225.imageshack.us/i/sbd.mp4/

Happy to put together a repro project and send it to you, but it’ll be later today (Aussie time) as I need to go to my day job…


maybe the same as this thread:


There is a passing resemblance - I’ll keep an eye on that thread.

If it is the same problem, then red_muze should see the same menu problems in PluginHost also.


Have come back to this after a few weeks away from it, and the problem has disappeared. I don’t recall anything from the Juce change log that looks like it might have fixed it. The only thing I can recall changing in my code is properly aligning the SSE up/down sampler objects from Laurent de Soras’ HIIR library. Not aligning these objects had been causing some intermittent zero referenced pointers at run time - not sure if that would have had much to do with a flickering menu. But all seems good now!


Perhaps the misalignment was making something throw an exception? If an exception got thrown during the paint routine it could cause flickering…


Hmm, didn’t see any exceptions firing though! As much as I hate unexplained, intermittent bugs - I’m glad this one has disappeared … for now at least :wink: