This is a backport to 1.14 of multiple commits from master:
* gui2/text_box: Implement I-beam cursor
d7f2595393
* Don't forcefully disable colour cursors
fc04268aa4
* Set the I-beam cursor's hotspot properly
c31047af47
This cursor is active when the widget has the mouse focus. You know,
like textboxes are wont to do anywhere else. Took long enough, although
there was an interaction issue with tooltips fixed in the previous
commit.
I still need to figure out how to make this work with GUI1 textboxes
(e.g. in-game console).
The colour version of the cursor was kindly provided by LordBob, and the
B&W version is my own.