Clone the QtComponents code here
git://gitorious.org/qt-components/qt-components.git
and checkout the "custom" branch.

Unzip the Qt.labs.components QML plugin (see attached Linux binaries) into your Qt4 folder.

Run the StretchBench.qml file. Drag the blue-box handles to increase the size of the shown button. Click/unclick the "Two-line text" option and note how the text on the button is drawn in the upper left corner of the button. Resize the button again and note how the text jumps to the centre, where it should be.