I have just noticed a strange behavior of ComboBox component. I am using it in DropDownList style. If I click on it, it drops down the list of items, as usual. But then if I click on some other component on the form, the combobox will not let me leave it, unless I select one of the items. I thought of adding onmouseleave event, but in that case it would close even if I move mouse out of combobox area a little, which is undesirable. What I would like to see is combobox losing focus whenever i click somewhere outside of its area. Is that possible?
Actually, I just did what you did: started a new application and threw ComboBox and TEdit. Ran the program. It drops down the list just as you said when you clicked on it. Also, when I clicked on the TEdit, the combobox closed automatically as expected. So, I don't know what is the problem with your program.