Make deselect-all instantaneous

src/terminal.go

@@ -1584,9 +1584,8 @@ func (t *Terminal) Loop() {
 				}
 			case actDeselectAll:
 				if t.multi {
-					for i := 0; i < t.merger.Length(); i++ {
-						t.deselectItem(t.merger.Get(i).item)
-					}
+					t.selected = make(map[int32]selectedItem)
+					t.version++
 					req(reqList, reqInfo)
 				}
 			case actToggle: