I decided to create a new combobox based on requests from the users of MSDN Windows Forms forum. It adds a new property to the regular
ComboBox so it can be set to read-only, much like the regular
Using the code
I made this code pretty straightforward so all you have to do is download the C# file enclosed in the ZIP file above and add it to your project. Build it, and the
ExComboBox should be available on the Toolbox.
You can change the way the disabled button looks by commenting the
ComboBoxRenderer line and uncommenting the commented portion of the code. You can set the color of the gradient that makes the button of the read-only mode by changing the colors of the
lgb on the
protected class DblPanel : Panel
protected override void OnPaint(PaintEventArgs e)
if (this.Visible == true)
Points of interest
I learned a bit while trying to add the read-only feature to the regular
ComboBox. It is interesting that the combobox does not have any sub-controls in it (check the
ComboBox.Controls.Count property and you will see it is 0); all is done by custom drawing. And, I also learned that there is no way to change this by overriding its
Paint methods as it doesn't happen there; and, I couldn't figure out where it draws itself, so I used a Panel to draw over the regular dropdown button.
So basically, all the functionality is kept from the original combo box except the ability for the user to change the selected item without disabling the control (many complained that setting the
Enabled property to
false made it difficult to read and didn't allow the use of custom colors).