CommandBase.checkIsAvailable?

CommandBase › checkIsAvailable?

Type: () => boolean

Whether the control can be used right now. When it returns false the control is rendered **disabled rather than removed**, so the strip does not reflow under the pointer as modes change — which on a phone means a mis-tap.

Re-read by ModalCommands.refresh. When omitted, the builder never touches the control's disabled state, leaving whatever CheckboxCommand.onInit / DropDownCommand.onInit set.