Popup Window with JGraphics

I'm currently developing a UI external which requires a modal pop-up window to appear occasionally to allow the user to make a selection between various data sources. Questions:

1. It is at all possible to create a modal window (ie, a floating window which stays on top and closes when the user clicks an 'OK' button)?

2. Can I draw the UI inside this window using  jgraphics, or would I have to use something like JUCE?

Code examples of either of the above would be greatly appreciated.