Custom widget plugin problem

I've created 2 Qt Designer plugins. One is a TabbedWidget and the other is a ComboBox.
Problem is when I insert it, it draws a border above and below it (see image) The comboBox plugin is wedged between 2 textEdits and you can see only half of it is visible, the bottom half is covered by the lower textEdit. I tried to reduce the QObject frame it sits in when I created it as small as possible but it won't reduce down to the size of the widget, there's always the title bar and some space below the widget, this (I think) is what is visible when used in another object..

How do I fix it ?

You may ask why would I want to create a comboBox plugin ?
Because I want to add several features (including sql lookup function) and re-use it several times in the in my Tabbed widget plugin and other places in my app.

The alternative was to duplicate code in the parent app.
If anyone has a better way, I'm all ears :)

Have you noticed Qt Designer's widget promoting feature? You could place a plain QComboBox on the form and tell Qt Designer to actually handle it as your custom combo box. It looks and acts like a normal QComboBox in Qt Designer but in the uic's generated code it will be an instance of your custom class.