Mouse Wheel Issue in Win - VST


When using the mouse wheel inside a viewport (ListBox or Viewport directly) the vertical scroll bar is immediately scrolls to the upper left regardless of
the position of the scrolling / the amount scrolled.

This only happens in VST mode, in standalone mode it works fine (it also works fine in Mac standalone / AU / VST )

I’ve found that in the func. doMouseWheel() the line:

const float amount = jlimit (-1000.0f, 1000.0f, 0.5f * (short) HIWORD (wParam));

Always returns 1000 in the problematic cases.


Hmm. Sounds like the same problem as this:

A similar issue is discribed here: When more than one Juce-based plugin is opened only the last opened will get valid mouse messages.

I just added this Component to the Juce demo plugin where the mousewheel worked fine with the Viewport:

class Container : public Viewport { public: Container() { editor.setSize(50, 200); setViewedComponent(&editor, false); } private: TextEditor editor; };
It was sized to show a scroll bar (50x150). Could it be you ran into the issue described above?


This workaround won’t work for me but the thread you posted seems to hold the answer.
I’ll check it out.


It appears that it only happens when I use a cheap mouse ( ‘Silver Line’ ) it works fine with a standard mouse.

How is this even possible? I thought Windows used standard generic drivers for mice (the vendor specific driver can be installed to gain additional features but without it, the generic driver provides basic functions). If this is the case then mouse behavior should be independent of the application. Unless, your mouse has installed some kind of special software that treats applications differently. Logitech for example can do this, customize the mouse for each app (usually a game).

When I first connected both of them Windows showed a messages that it is installing their drivers, so I guess it’s a specific driver issue.