Setting Tooltips only for longer text width WPF COMBO

Hi,

I am creating a WPF application. My application has a WPF combo box in which i am embedding a Text block in it.

I am filling some items to the combo. My question is i want the combo box to display full text for the text whom length is smaller than the combo width, and for the longer widths i need to display the text followed by dots.

I am able to fill in the contents to the combo and also able to set the tooltip. My question is i want to enable the tooltip only for longer texts and NOT for shorter texts. How to add the conditional check ?

Code

for (int count = 0; count < 100; count++)

{

TextBlock textBlock = new TextBlock

{

Text = count

Width = combobox.Width - 30,

};

textBlock.ToolTip = textBlock.Text;

combobox.Items.Add(textBlock);

}