Getting mouse clicks in the right place

I’m having trouble getting mouse clicks where I need them. I have a view class, based on layouteditor from jucer, and I then have:
a viewport (with a magnifier)
and in that, a workspace,
and in that a content view - with other stuff in it.

The original class has a lasso member and related functions to create it. But it doesn’t get any clicks in the viewport area. If I tell the viewport not to get mouse events (false, false) then the lasso does get created - but the viewport scrollbars etc. don’t work.

Am I barking up the wrong tree? Do I need to detect the lasso clicks somewhere else?