src/vs/workbench/contrib/files/browser/fileActions.ts/BaseSaveAllAction/updateEnablement
class BaseSaveAllAction:	private updateEnablement(workingCopy: IWorkingCopy): void {
		const hasDirty = workingCopy.isDirty() || this.workingCopyService.hasDirty;
		if (this.lastDirtyState !== hasDirty) {
			this.enabled = hasDirty;
			this.lastDirtyState = this.enabled;
		}
	}