Toolbar redraw causes unwanted selection

[JD Smith]

When two windows in a single frame have different toolbars displayed
which occupy a different number of rows, changing input focus between
them by clicking with the mouse causes an unwanted selection to occur.

Steps to reproduce:

- Open two files in two windows split vertically in a single frame.

- In the bottom window, M-x gdb [Ret]

- Resize the frame horizontally so that the GDB toolbar icons just fit
  in a single row.

- Switch to the top window in the frame by clicking on it with the
  mouse, without dragging.

Since the normal editing toolbar now occupies *two* rows, the text is
shifted down as the toolbar is redrawn, and several lines of text are
selected, even though no drag was performed.

This has real-world applicability for idlwave, since its toolbars
occupy two rows even with normal frame widths.

JD