Most of the models were just calling did_update anyway, which is
pointless since it can be unified to the base Model class. Instead, code
calling update() will now call invalidate(), which functions identically
and is more obvious in what it does.
Additionally, a default implementation is provided, which removes the
need to add empty implementations of update() for each model subclass.
Co-Authored-By: Ali Mohammad Pur <ali.mpfard@gmail.com>
Applications previously had to create a GUI::Menubar object, add menus
to it, and then call GUI::Window::set_menubar().
This patch introduces GUI::Window::add_menu() which creates the menubar
automatically and adds items to it. Application code becomes slightly
simpler as a result. :^)
go-up.png and go-down.png don't exist (and would look silly here, with
the buttons being next to each other horizontally). Use go-back.png and
go-forward.png instead.
When holding ctrl and scrolling, the page will be zoomed in an out.
When zoomed in on a page, scrolling with move vertically up and down
the page (or horizontally if shift is being held).
In order to speed up zooming, zoomed bitmaps are cached per-page at
each distinct zoom level. This cache is cleared every 30 seconds to
prevent OOM problems.
