Rounded Combobox?

Hello!

I am writing a little application to manage my library. In the input form I am using textfields as well as comboboxes. For the textfields I use the following declare to get rounded corners, which works very well:

#If TargetCocoa Declare Sub setBezelStyle Lib "Cocoa" Selector "setBezelStyle:" (handle As Integer, value As Integer) setBezelStyle(Me.Handle, 1) #EndIf

Unfortunately this declare does not work with the comboboxes, or that is to say it just makes a text indent like in the textfields, but the left corners are still not rounded (see image).
Is there any possibility to get rounded comboboxes to get a consistent look for the input form?

EDIT: Sorry for the huge image – I don’t know how to get it smaller here…

Preview --> Resize.