tree - have useAltAsMultipleSelectionModifier

[jrieken]

re #64727

Today workbench tree have useAltAsMultipleSelectionModifier which is used by the explorer, open editors view, and outline and we need some sort of equivalent for the new tree world

[jrieken]

cc @isidorn

[joaomoreno]

From the code, this should work. I've tested the Watch Expressions tree and switching the setting does alter its behavior. Doesn't work for you? You have to pass in multipleSelectionSupport: true to the tree options, maybe that's the difference?

[jrieken]

switching the setting does alter its behavior.

You that it reflects that in the corresponding event?

[jrieken]

Today I use it like this: https://github.com/Microsoft/vscode/blob/850c03010d475b0b14802ac8811dd1e716846e23/src/vs/workbench/parts/outline/electron-browser/outlinePanel.ts#L593-L613

[joaomoreno]

Oh I wasn't aware these workbench lists and trees re-expose that stuff... pushing exposition of that boolean.