TComboBox - Delphi Usage Examples, Tips and Tricks

Sizing The ComboBox Drop Down Width - No Cut Off For Right Edge Placements
When a combo box is in dropped down state Windows draws a list box type of control to display combo box items for selection. When the length (of a string) of items exceeds the width of the combobox, the items are displayed as cut-off! Here's how to ensure all ComboBox items are visible when drop down list is displayed.

Drawing a TComboBox: Color Pick List, Font Pick List
Graphical Drop Down List - a Combo Box of Colors; and a True-Type Font Picker.

Implementing OnMouseOver for Items in a TComboBox, with Custom Hints
Here's how to get the caption of an item in a TComboBox as mouse hovers over an item when the ComboBox is in drop down state. Use this "trick" to get the object associated with the "pre-selected" item in a combo box, or to display a custom hint for each item, for example.

Store a String (or an Object) Along with a String in Combo Box
There are situations when you want to display a list of strings to the user, for example in the list box control, but also have a way to store one more additional string along the one displayed to the user.

How to Right Align Items in a TComboBox
Suppose you have a ComboBox displaying currency values, or more generally numbers. Here's how to display the items in a ComboBox right-aligned...

How to complete partial strings typed into a combo box
The example shows how to complete partial strings typed into a combo box. The code represents the OnKeyPress event handler of the combo box, which performs most of the default keystroke handling before finding matching list item and updating the text.