I'm using 2.3b and I've added colors to the leave calendar so that my leave administrator who uses the LN 7.0 client can easily view the difference (even though it should show the three letter LTC code which it doesn't [placed a bug request for that already]).
I think this is something you might want to do, it is easy to do and it highly increases the usability of the application.
I've easily done this by creating a color column in the leave calendar view and set that column to "use value as color", hidden the column, and then used a simply formula to calculate the colors like this:
@If(LTC = "VAC"; 64:49:240; LTC = "SCK"; 255:0:0; 20:171:16)
Since users can make thier own leave types this may be a little more complicated though…
The key here is that the LTC field must be created on the AL form which is currently a bug.