Question

If I set a Windows Forms CheckBox.Checked = true, and it’s already true, does the widget redraw itself?

I would expect not, if it’s just directly setting the value as there will be no change. But I can imagine that there might be some magic code in there that sets a dirty flag upon setting the value, regardless of what it already was.

I just want to know if I should be doing stuff like this to prevent extra refreshes:

if (TheBox.Checked != checkBool)
{
    TheBox.Checked = checkBool;
}

Answer 1

If the Checked value doesn’t change, the Paint event doesn’t fire, so I assume that means it isn’t redrawing itself. You can see this by handling the CheckBox.Paint event and putting a breakpoint in the handler method.