X, Y, Width, and Height are the dimensions of the check box.
Value is the checkbox state: CheckBox.False, CheckBox.True or CheckBox.None for an unknown state.
Flag is a combination of style drawing flags.

Note:

Different toolkits behave differently with this function.

As a general example if you supply width and height size as 32x32px QT5 will paint a checkbox 32x32px in size but GTK3 will only paint a box of 22x22px inside a 32x32 frame regardless of what size you request. If you request 16x16 the image will be cropped.

To truly get different size checkbox other than 22x22 with gtk3 you must first paint the 22x22 box and then stretch the image.

Ie..

Dim hPic As Picture = New Picture(22, 22, True) ' create a blank 22x22 Picture object

Paint.Begin(hPic)
Style.PaintOption(0, 0, 22, 22, iValue) ' paint the 22x22 checkbox
Paint.End

hPic = hPic.Stretch(16, 16) ' Stretch the picture to the desired size