Experimental results (cont'd)

Experimentation also indicates that any vertical dimension up to about 880 is allowable on my machine.

(There doesn't appear to be a divisible by four requirement for the vertical dimension.) 

I suspect that the wide border at the top of the window (see Figure 1) causes the limit on the vertical dimension to be less than 900.

The overall size of the window is larger than the specified dimensions which apply only to the gray area in Figure 1.  This is particularly true with respect to the vertical dimension.