Create a combo box with multiple selectable values
- Right click in the (Ribbon) menu at the top and click "Customize the Ribbon...".
- On the right side (Customize Ribbon) with "Main Tabs" selected, enable the checkbox "Developer".
- Click OK.
- Go to the "Developer" Tab (in the Ribbon menu) and click "Visual Basic".
- Right click on the worksheet (on the left side) where you want to use a Multi-Value-Combobox and select "View Code".
- Copy the code (everything) from Code.vba into to open document.
- Save and close the editor.
- Select a cell (or multiple cells) that you want to have a Multi-Value-Combobox.
- Go to the Tab "Data" (in the Ribbon menu) and click on "Data Validation" -> "Data Validation".
- In the "Data Validation" dialog (that just opened) in the "Settings" Tab set "Allow: List" and "Source" to a range of the allowed values.
- Click OK.