I am totally new to infragistics controls.
There are few item added when i am selecting "All" item, it should display all item except "All" in the textbox area. How to achieve this logic.
Using UltraComboeditor we do not have inbuilt select All option or functionality. So may be you are adding this All item in the list your own. The behavior you are expecting wont work.
The closest you can get is using UltraCombo (not UltraComboEditor) and do NOT add an "All" item on the list, but rather, turn on header checkboxes for the checkbox column so the user can select/deselect all. And setting Header’s Caption to "All" would show up to select all but not in the text area.
I attached a sample application of the UltraCombo for the reference.