Comment 1 for bug 1318339

The bug is not limited to the Plotter export extension, but potentially affects all extensions where tooltips are used in page elements (tabs) :

Works:
<param name="param" type="string" _gui-text="myparam" _gui-description="mytooltip">myvalue</param>

Fails:
<param name="tab" type="notebook">
  <page name="tab1" _gui-text="mytabtext">
    <param name="param" type="string" _gui-text="myparamtext" _gui-description="mytooltip">myvalue</param>
  </page>
</param>