BackgroundColor 
I do something like this:
```nim
# setup for queryButton
var queryButton = newButton(" Run Query ")
queryButton.fontSize = 18
queryButton.textColor = rgb(30,144,255)     # color ok
queryButton.backGroundcolor = rgb(0,255,0)  # no effect ?
rightMenuContainer.add(queryButton)
```
 textColor method  works for button and labels only
 other controls eg textBox does not show any text or background color changes at all.

PS.: nigui is really nice  and hopefully there will be a comboBox widget 
        I am using it to display output from sql queries.
       Here running under openSuse Tumbleweed .