I just tried out the responsive resizing for groups and it's not bad! It does make a lot of assumptions, so you end up with behavior you might not expect, but with some tweaking, you can get what you're looking for.
Here's a quick GIF of what I made: Window resizing example
Haven't tried Affinity Designer constraints feature. The Sketch implementation is really simple. It just maintains the position of the layer relative to the nearest corner of the group. Likes like it works pretty well from your demo.
Can you also set the grey background to "Resizing" based on the text with which is has been grouped?
E.g. with a button, when the label increases in size from let's say "Button" to "This button" — will the background that automatic resize with the appropriate padding?
This new stuff is all nice and well, but the fundamental workflow remains broken: where is in-context editing of symbols? When can we copy symbols from another document and not be stuck with a duplicate list of symbols? And when do styles copied from another document sync again?
This all worked much, much better before the big symbols and styles update. I remain disappointed that the Sketch team doesn’t fix this first. It’s a monstrous issue for anyone working on multiple large documents that are part of one design system.
Too bad the weird Sketch Mirror bug causing internet speed to drop doesn't seem to be fixed yet. Breaks my workflow even more than the Symbol imperfections.
Really nice to be able to have different sizes for the same symbol and the scaling is a really nice addition. Hope they add constraints somewhere down the road to get a more predictive and dynamic scaling.
While on the subject of scaling, why not have a scale value? So you can select an object that is 100x100 and scale it too 200x200 by changing width and height or by setting scale to "2" or "200%". Most 3D applications have scale values so it's easy to keep track of what the original size was, could be helpful for symbols too so you know what size it was made for initially.
this is crazy. just today I discuss sketch, nested symbols and the fact that I had to create multiple symbols for different sizes with a colleague. I said this is on top of my wish list... and look now... A new beta! It's like xmas came early! Thx Sketch team