I am trying to resize the columns in a register window to give more space
to the Transfer column and less space for the Description.  I can move the
slider between the two columns, but it snaps back to its old location when
the mouse is released.

From what I can see, the Description column can't be shrunk below a certain
size.  It is easy to shrink the other columns to nothing.  It is possible
to expand certain columns like "R" to large sizes.  But it is impossible to
expand Transfer except by shrinking all the columns to the right of it.
In fact, it looks like moving the separator between Deposit and Withdrawal,
gradually moves the separator between Description and Transfer to the right
squeezing all the other columns.