Currently, ComposerWidget is reasonably complex, since it handles not only managing the composed messages themselves, but also editing actions related to the ComposerWebView.

To improve this, the class and its UI file should be split up into two: A ComposerWidget and a ComposerEditor class, the latter including the editor toolbar (bold, italic, etc) and menu, and the ComposerWebView instance, and which manages actions for the toolbar and any related code. Some functionality may also be able to be moved to ComposerWebview, but that should mostly be kept as the interface between the client and WebKit, and not much else. The attachments UI and code should probably remain in ComposerWidget for now, but that aspect of it should get cleaned up a lot anyway when Bug 778727 lands.

This may solve Bug 741741 (if that is even still valid) but also allow removing the focus in/out hacks in subclasses of ComposerContainer.