Hi! Just starting to use Glyphs 3. Right-click in the character groups doesn’t show the pop-up panel using the trackpad of my laptop. I’ve tried with the Wacom pencil and it works so I guess this is a bug that can be solved.
That is new: That is works with a Wacom and not with the trackpad. But I suspect there is something wrong with your trackpad settings as it works for so many people including myself.
Try Control-Click on the trackpad. If that pulls up the context menu and a right click on the trackpad (lower right corner of the trackpad) doesn’t, then check the System Preferences > Trackpad > Point & Click setting for Secondary Click. The secondary click can be set to lower right, lower left, or two finger click.
Ctrl-Click is what I was using in Glyphs 2 but doesn’t work in Glyphs 3. That’s the reason for the confusion. I’ve changed the settings of the trackpad and Right-Click works now in Glyphs 3 
(two-finger which was my previous option doesn’t show the characters panel if you want to check that)