src/vs/workbench/browser/parts/editor/editorDropTarget.ts/DropOverlay/hideOverlay
class DropOverlay:	private hideOverlay(): void {
		const overlay = assertIsDefined(this.overlay);

		// Reset overlay
		this.doPositionOverlay({ top: '0', left: '0', width: '100%', height: '100%' });
		overlay.style.opacity = '0';
		overlay.classList.remove('overlay-move-transition');

		// Reset current operation
		this.currentDropOperation = undefined;
	}