I find that various combinations of plugin-added custom quicktag buttons disrupt each other's functioning.
For example, with contact-form's button active, custom buttons before it, like say iimage-browser and ca-cpicker, no longer open their popup windows, or do anything.
Ditto with photopress and other custom buttons. Perhaps the autors are not implementing their buttons 100% correctly, but how might I investigate myself? I can't see the custom buttons in quicktags.js, so where should I look?