You're not giving us much to work with. How about ZIPping your project (after doing a Build > Clean) and attaching the ZIP to a reply here?
I use the template to create a SDI program and add one menu item (tDialog) under the File menu. It opens a Dialog. The Dialog has two Combo boxes. I could add the items now, but when click the Arrow, it doesn't show the list correctly, only a narrow area. Hard to scroll up & down.
It's better the software's default could display correctly at the first place. That is showing a scroll bar with 2 lines with one up arrow and one down arrow. Or a default area bigger than 2 lines. If total items less than default area, no scroll bar is needed.
Then, If the user need to change, he could go back to design.