Question

I have this code

if (IsValid(textBox.Text))
{
    toolTip.Hide(textBox);
}
else
{
    toolTip.Show("Please enter an valid text", textBox);
    textBox.Select();
}

It work fine as normal tooltip, but when I set IsBallon to true on toolTip it stops showing at all.

Answer 1

This seems to be a known issue:

http://social.msdn.microsoft.com/forums/en-US/winforms/thread/1b0b026f-90ea-4cd3-b372-45de2d60ca0c/

and

http://www.debugging.com/bug/20204

Try the solution suggested in the latter:

I’d use regedit to check the registry setting for which the key is as follows:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\EnableBalloonTips
If it’s zero, they’re disabled. You’d then need to change it to 1 and reboot the machine.

(EDIT: Adjusted the registry key after reading further in the linked page)