RichTextBox behaving weirdly

[Paul E Collins]

I want to colour certain characters as they are typed in a RichTextBox. I
started with this simple event handler.

private void rtb_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar >= ' ')
{
this.SelectedText = e.KeyChar.ToString();
this.SelectionColor = Color.Blue;

e.Handled = true;
}
}

Why does this code not colour the first character typed into the box? It
works for subsequent characters.

Eq.

[Paul E Collins]

Hmm, okay, it seems that setting SelectedText changes the selection. Here's
what I used in the end.

if (e.KeyChar >= ' ')
{
this.SelectedText = e.KeyChar.ToString();

this.SelectionStart--;
this.SelectionLength++;
this.SelectionColor = GetColourForChar(e.KeyChar);

this.SelectionStart++;
this.DeselectAll();

e.Handled = true;
}

Eq.