| buttonRect | ウィンドウの位置からボタンが決定されます (Descriptionを参照)。 |
| windowSize | ウィンドウの初期サイズ |
ドロップダウンの動作とスタイルを持つウィンドウを表示します
The window is styled in the same way as a PopupWindow. The window is automatically closed when it loses focus. Note this function auto-fits the window to screen while trying to place it first below then above the button it was triggered from. This means the windowSize might change when fitting it to screen, so you should make sure you read the 'position' afterwards to check whether the size was cropped.