Hi Michael,
Here is a minimal sample that implements the ListView and ComBoBox as dropdown of the cell in a grid. It also shows you How to control dropdown container in a cell of the grid.
DropDownUserControlSample.zipAlso refer to the "DropDownUserFormAndUserControlSample" browser sample for more details.
\Syncfusion\Essential Studio\4.4.0.49\windows\Grid.Windows\Samples\CustomCellTypes\DropDownFormAndUserControlSample\cs
Best Regards,
Haneef