Unlike the behaviour in Go 11, popup menus or drop-down lists do not close when a selection is made.
This looks like a bug but I wanted to check it was not just me that is seeing this.
I feel the 'rotating barrel' UI element in 12 is doing a very poor job all around:
Static size means it will be the wrong size more often than not.
Remaining open after selection (if it's not a bug). Obscures other UI elements after selection.
Scroll bar almost invisible.
More interaction required (scrolling/closing).
The v11 implementation was almost perfect:
Dynamic size resulted in often no scrolling being required to see all objects.
High contrast ideal for outdoor use.
Closed automatically when a selection had been made.
Scroll bar showed the position in the list.
Why the design change?
Go really needs a proper iOS popup menu/list along the lies of the v11 implementation with the option of a number/letter picker along the right edge and decent methods to allow type ahead.
A lot of iOS apps have this capabiltiy with huge lists.