I found an open source-- Firebreath which aims to be a cross-platform plugin architecture, I want to use this to implement a security controls in firefox chrome and so on.
I can get the hwnd ,but i have no idea at how to insert some control like an edit box or button into the hwnd window.
Can I use the MFC or ALT or something else in Firebreath? I'm newbie in browser plugin, I need some help.
AFAIK nobody has been able to get MFC working with a FireBreath plugin, mainly because FireBreath is built on ATL which seems to be incompatible with MFC.
Other than that, though, just because it's a browser plugin doesn't mean there is anything special or magical about it; the real question you want to look into is how to create a HWND and add controls to it using C++. That's not a FireBreath, firefox, or plugin question, it's a question of learning windows programming.
While you're working on that, remember a few key rules:
You are not ever allowed to block the main thread. Don't do it. Please don't argue with me on this one, it'a a really bad idea.
the HWND that you are given in the AttachedEvent does not belong to you. You can draw to it, you can do things with it, but be aware that it is owned by the browser and you don't get to decide things about its lifecycle, etc.
I'm not sure what you're trying to do, but the #1 rule to know about plugins is this: If you can solve the problem without using a plugin, don't use a plugin. In addition, most people avoid doing an actual UI inside a plugin simply because it is a bit of a pain to do with C++, so most often people make the UI in html and use javascript to interface with the plugin.