On macOS, native_menu::sync reads every row of the menus (each
command's enabled and checked state, and each label) whenever
state_hash changes, and the macOS backend updates the AppKit items
whose label, enabled or checked state changed. The hash included the
active document's revision, and Session::preview makes a new revision
at each step of a drag, so the app read every row again at each step
of a move, scale or shape drag. In a release build on an M2 Max, that
took about 1.5 ms a step with one object selected, and 13.8 ms a step
with 5,001 objects selected.
While an interaction is open, state_hash leaves the revision out.
Move, scale and shape drags, dialog previews and the font menu's
preview are interactions. The menus are read when an interaction
begins and again on the frame it ends: when a drag's button is
released, when Escape cancels a drag, when a move is dragged onto a
panel, when a dialog's preview is applied or canceled, when the font
menu's preview ends, or when a control request such as
ui.dialog.cancel ends it. They are still read on a click or a key
press during an interaction.
docs/development.md says when the menus are updated during an
interaction.
fb2089aaf5