There are a number of ways you can customize the look & feel of your RadComboBox control:
To change the basic dimensions of RadComboBox:
Use the Height property to control the height of the drop-down list. If you do not set Height, the drop-down list sizes itself automatically based on the number of items in the list. If the value of Height is too small to display all of the items in the list, a vertical scroll bar appears on the drop-down list.
Use the MaxHeight property to allow the height of drop-down list to vary depending on the number of items. If the number of items is large - the height will not exceed the MaxHeight value.
To change the height of the input area of the control, edit the CSS style that is applied to the input area. The CSS style for the input area is called .rcbInputCell. Thus, for example, to set the height on the Black skin, use the CSS style .RadComboBox_Black .rcbInputCell:
Set the Width property to specify the width of the input area of the control.
Set DropDownWidth to specify the width of the drop-down list. If DropDownWidth is not set, the drop-down list gets the same width as the input area of the control. The oposite, however, is not true: setting DropDownWidth but not Width does not resize the input area to the same size as the drop-down list. If DropDownWidth is too narrow for the items in the list, a horizontal scroll bar appears in the drop-down list.
To change the overall look and feel of RadComboBox, set the Skin property.
To change the way the drop-down list appears or disappears, use Animations.
To change the look of an individual item in RadComboBox, use its CssClass property and set up the CSS styles as needed.
CssClass property defines style for the input of RadComboBox.
DropDownCssClass property defines style for the drop-down list of RadComboBox.
To provide a right-to-left look and feel, use the dir="rtl" attribute. If you do not want the complete RTL support, but want to move the drop-down toggle to the left of the input area, simply set the RadComboBoxImagePosition property to "Left".
To associate a label to RadComboBox set its Label property to the text that you want to appear next to RadComboBox (added in Q1 2010 release).
To remove the drop-down arrow set ShowToggleImage property to false.
To cause the drop-down list to expand on the page somewhere other than the default (immediately below the input area), set the OffsetX and OffsetY properties. OffsetX and OffsetY indicate the horizontal and vertical offset of the drop-down list, in pixels, relative to the input area.
The drop-down list automatically expands to the opposite direction when the screen boundaries would otherwise be crossed.