Update:

I think I nailed it, hinted by this post.

So I subclassed QProxyStyle as AndroidStyle and reimplemented QProxyStyle::pixelMetric this way:

Qt Code:
  1. int AndroidStyle::pixelMetric(PixelMetric which,
  2. const QStyleOption *option,
  3. const QWidget *widget) const
  4. {
  5. int metric = QProxyStyle::pixelMetric(which, option, widget);
  6. switch (which) {
  7. case PM_IndicatorWidth:
  8. case PM_IndicatorHeight:
  9. return 2*metric;
  10. default:
  11. return metric;
  12. }
  13. }
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and I set this style in the main function like this:
Qt Code:
  1. QApplication a(argc, argv);
  2. a.setStyle(new AndroidStyle);
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