TaskbarTestCases: add a nested function to wait for a popup menu is shown
TaskbarTestCases: add a nested function to wait for a popup menu is shown

vasily-v-ryabov/pywinauto,pywinauto/pywinauto,airelil/pywinauto,MagazinnikIvan/pywinauto,cetygamer/pywinauto,drinkertea/pywinauto