Switch HTML output window back to NSWindow

The motivation for using a panel was to avoid the window from becoming main (so key equivalents would be sent to the document window, if not handled by the HTML output window). Unfortunately window ordering ignores non-main windows when a window is closed meaning that bringing up the Find dialog from an HTML output window and then closing it, would bring the current main window to front, eclipsing the HTML output window.
Let OS handle keys for Go to Tab submenu

My memory is a little vague here, but I believe the point of handling the menu keys was to workaround a bug in NSMenu.

The bug was that NSMenu would look at (the target of) cached menu items, probably for UI validation, so potentially sending methods to unretained objects, which could lead to a crash. Several workarounds were attempted (like clearing the target property after the menu had been displayed) but the only effective one was overloading key handling.

I’m quite sure though that this bug is no longer relevant.
WIP: Add scope bar to file chooser