These fields are intended to carry the real meat of a drag operation,
and the "text" is just for what we show on screen (alongside the cursor
during the actual drag.)
The data field is just a String for now, but in the future we should
make it something more flexible.
This makes GTreeView able to support multi-column models!
Only one column can be the "tree column", this is column 0 by default
but can be changed by overriding GModel::tree_column().
This breaks GSortingProxyModel selection preservation across resorts.
I'm not yet sure how we're going to solve that, but it's going to have
to work a bit differently than before, since the model itself no longer
knows what's selected.
Selection is now managed by GModelSelection which allows us to select
any arbitrary number of items, and to have different selections in
different views onto the same model. Pretty sweet. :^)
This was a workaround to be able to build on case-insensitive file
systems where it might get confused about <string.h> vs <String.h>.
Let's just not support building that way, so String.h can have an
objectively nicer name. :^)
This is just for convenience really. It lets you skip const_casting in
all the code that calls this API, which you would basically always be
doing otherwise.
Instead of LibGUI and WindowServer building their own copies of the drawing
and graphics code, let's it in a separate LibDraw library.
This avoids building the code twice, and will encourage better separation
of concerns. :^)
