Is it possible to size-out of a position or does one have to close the position entirely?
You can turn on aggregation mode and it’ll work like Invest / ISA
Ah, brilliant. Thanks (again) @phildawson
On Desktop, click on the open position (or right click then click edit), move to Market Order on the left, then you can reduce (or increase) your position.
When I tried that it shorted the shares.
Strange! It always worked for me.