Some issues with scrollbars
```nim
import nimx.window,
       nimx.text_field,
       nimx.scroll_view,
       nimx.system_logger,
       strutils

runApplication:
    let wnd = newWindow newRect(40, 40, 640, 480)
    let tv = TextField.new newRect(40, 40, 100, 100)
    tv.resizingMask = "wh"
    tv.text = "abcdefgi\n".repeat(20)
    tv.multiline = true
    let scroll = newScrollView tv
    wnd.addSubView scroll
```

The scrollbars are incorrect initially. It appears correct after I select some text, minimize the window and then bring up the window. Is my code correct?