gimpo:
I can confirm you that pressing the upload-button or selecting Sketch -> Upload Using Programmer are doing the same thing/action when "USBasp" is selected as programmer.
[/quote]
Which hardware package are you using (e.g. Arduino AVR Boards)? Normally pressing the upload button should be the same as Sketch > Upload, not Sketch > Upload Using Programmer. Holding Shift while pressing the upload button does the same thing as Sketch > Upload Using Programmer. As I said before, there are some board definitions where that is not the case but the Arduino AVR Boards Pro Mini definition is not one of them.