Results:
17" LCD Monitor.
Auto sizing with screen resolution set to 1280x960 (a multiple of 1024 x768) helps quite a bit with, but display of data is still not properly centered in the boxes (too low with bottom of figures truncated). With LCD monitor set to 1024x 768 (A bit out of the normal useful range these days), the data is not truncated., but actually slightly overlaps the bottom of the boxes.
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Using a 14", 1995 vintage, CRT monitor at the limit of its resolution (1024 x768) the display is correctly presented at all times. This is presumably more like the environment for which Mach3 was designed.
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Thanks for your help