I am trying to create a Popup menu, which allows the user to select multiple items at once. The proble, with the JUCE Popup menu: it closes down, as soon as you select an item. But I want to create a Popup menu, which stays open after you selected one item and allows you to select additional items. Something like this:
Maybe some of you have done something similar? And can give hints on how to best implement such a feature? 
Not exactly the same, but there is the MultiChoicePropertyComponent which we use to do something similar in the Projucer:
Hi Ed,
Ah, did not know that multi-choice component. Cool. Thanks!
But just realized, that Popup menu might work after all.
I found out, there is an option to add a “PopupMenu::CustomComponent” as an item. And the good thing is: if you click on this custom component, the Popup menu does not disappear. In other words: you can implement your own mouses handling for that CustomComponent. And thereby I should be able to make a Popup menu, which allows multi-select.
Just out of pure curiosity: and then, how does the user closes the pop-up once he has made all his desired changes?
Well, he would simply click anywhere on the screen, where there is no popup menu.
That closes the popoup menu and applies any changes he made in the selection.
