Hello Flavio,

I have been investigating into the functionality to place a "header checkbox" in the XamMultiColumnComboEditor, and at the moment, there does not exist a built-in way to do this, although you can do some styling to allow this functionality.

In order to achieve your requirement, I would recommend inclusion of the default style for RowSelectionCheckBoxHeaderCellControl. This default style can commonly be found in the generic.xaml file at the following directory when you have an Infragistics WPF product installed:

C:\Program Files (x86)\Infragistics\<your version here>\WPF\DefaultStyles\XamComboEditor

Once you have included this default style, I would recommend modifying it such that there exists a Checkbox in the default template as well. On check or uncheck of this checkbox, you can then select or deselect all items in the XamMultiColumnComboEditor.

I have attached a sample project to demonstrate inclusion of the default style. I hope this helps you.

If you would like to see this functionality included in a future version of the XamMultiColumnComboEditor, I would recommend suggesting a new product idea for this feature at https://www.infragistics.com/community/ideas/i/ultimate-ui-for-wpf. This will place you in direct communication with our product management teams who plan and prioritize upcoming features and development based on community and user feedback.

Please let me know if you have any other questions or concerns on this matter.

MultiComboHeaderCheckbox.zip