none of the (documented) E4 CSS attributes address control sizes.

Also tried adding a Control listener to listen for resizes and set the size, however this results in incorrect layout. It's like I need a "Sash" object to move the sash bar, but haven't been able to get one.

Also, I found how to dig the SashLayout out of the control hierarchy, but SashLayout does not allow external modification (no methods for changing size).

Also tried changing the MPartStack Container Data upon each resize, to re-set the container weight. That causes weird behavior: you can drag the sash to resize wherever you want to, then when you're done it pops back to the size I set in the code.

Also tried adding a mouse-move listener to the composite containing the sash, and restrained mouse cursor movement when the width was not within the min/max. Very clumsy and never got it working right.