Comment 0 for bug 1399245

<KnobComposed>
  <Size>40f,40f</Size>
  <BackPath scalemode="STRETCH">backdrop.svg</BackPath>
  <Knob>knob.svg</Knob>
  <MinAngle>-230</MinAngle>
  <MaxAngle>50</MaxAngle>
  <Connection>
    <ConfigKey><Variable name="group"/>,<Variable name="control"/></ConfigKey>
  </Connection>
</KnobComposed>

In my example, knob.svg & backdrop.svg both have a base size of 30x30.
knob.svg but is scaled as foreground image to 40x40. backdrop.svg as background image should scale as well to 40x40, but instead sits lonely in the corner.

Workaround is to make the backdrop.svg the same size as the actual <KnobComposed widget size (40x40). This removes the flexibility the tiling/stretching <BackPath> promise to offer.

PS. Scaling works fine with <BackPath> of <WidgetGroup>. Probably other widgets supporting <BackPath> are affected (untested).

See recent conversation: https://github.com/mixxxdj/mixxx/commit/a1de569348b4f91eb28c079bb07164a81eb800bf
Commit history: https://github.com/mixxxdj/mixxx/commits/master/src/widget/wknobcomposed.cpp