Resizing and window dimensions can be handled well across all the main browsers but it's my understanding that it still requires some javascript stub code in order to have predictable/repeatable behaviour across most browsers.

SMS I assume generates Javascript from pascal code - I'm also assuming that it has at least a rudimentary, static Javascript API - an ideal fix might come from altering the javascript API rather than coding around it in the pre-translation pascal code.

for a simple solution, you may want to run a timer that fires every second or so that manually queries and compares the screen dimensions. This way if they're not updated correctly in the normal chain of events on a given browser - it will 'correct' a moment later - this technique is evident on many sites that have elements that seem to be delayed in their re-positioning after a resize.

It's not problematically ideal - but it works - if you delay initial rendering (just black out the window) for a couple of seconds on load - then any 'ugly' snapping of dimensions will be hidden.