Different configurations for different games / apps and within app scenes
Configure generic window positions specific to a game or app, and drag and drop windows from the desktop into position. For example, in Elite: Dangerous, you could pre-position windows in your cockpit for streaming video or external tools, and just drop a source in -- or even better, remember the source and automatically try to restore it -- so that you don't have to fiddle with positioning every time.
Similarly, allow the game / app to control which configuration is in use at any particular time. Again, using Elite as an example, you might have different configurations for different ship cockpits, and you would certainly want a different configuration when in the menus.
Yes please, a way of saving a layout
Or give us a way of saving a layout for next time
Yes, if "themes" or "templates" could be used to define/store the size/position of assets that could be very useful (eg: in an XML format). ie: So you return to a game/program and simply re-apply an already defined "template" to get apps setup as previously defined.
If these could be updated in real time and Dash respond to them, we enter some very interesting realms. eg: Of other programs being able to dynamically adjust assets in another program.