Combo box off center with centered parent container
OS: Nobara linux 37

The code:
```nim
import nigui
app.init()

var window = newWindow("window")
window.width = 350.scaleToDpi
window.height = 200.scaleToDpi


var baseContainer = newLayoutContainer(Layout_Vertical)
baseContainer.widthMode = WidthMode_Expand
baseContainer.xAlign = XAlign_Center
baseContainer.yAlign = YAlign_Center
window.add(baseContainer)

var Combo = newComboBox(@["1", "2", "3"])
baseContainer.add(Combo)

window.show()
app.run()
```
in theory, it should center the combo, but it leans to the right:
[![Screenshot-from-2023-04-16-14-03-27.png](https://i.postimg.cc/MGKkKqTz/Screenshot-from-2023-04-16-14-03-27.png)](https://postimg.cc/5XGKscLr)

other widgets like buttons and text boxes do center