Plugin MouseWheel Issue VST 32BIT && Windows 7


Jules, Fabian, Timur, please help us to getting the MouseWheel working with Windows7 && 32bit Plugin-Hosts

How to reproduce the issue:

-> open JUCE VST A GUI on 32bit-DAW on Windows7 

-> open JUCE VST B GUI on and use the mouse wheel over a slider (will work OK)

-> After opening  JUCE VST A  plugin again, use the mouse wheel over a slider. Independently from the wheel direction it will always go up in rather large steps.

It seems the problem is specific only to Windows 7 and 32 bit. 64bit and/or Windows8.1 is working

Its a serious problem because, for example, if the slider controls volume, the volume goes up to the max volume in very short time.

Please help us!!!



It seems the MOUSEHOOKSTRUCTEX_.mouseData some how is muddled somehow, but is still okay.

Maybe there is some conversion error, when the other hook reposted from the other plugin ?!?!!?

Maybe there is a better way to get the WheelData (Subclassing Window Proc?!?)

I would really appreciate if someone from the JUCE-Team accept the challenge to fix this issue, because its serious issue with all JUCE-Plugins on Windows7/32bit.

Any Comment?




This seems to be a known issue of 32-bit apps running under a 64-bit Windows 7 OS version. See for example:

Can you confirm that your OS is in deed 64-bit but the DAW/plug-in is 32-bit? Can you try installing the hotfix from the above link to see if this fixes your problem? A quick google search suggests that there is no easy workaround other than for users to install the hotfix.

BTW: I can confirm that the issue does not occur under Windows 8


EDIT: Broken link fixed


That's it! Thank you very much

Yes it was Windows 7/64!

Its a pity this isn't an automatic update