static JSplitPane setSplitPaneOnFirstShowing(Component c, double value, int delay default 0) {
  final JSplitPane sp = first(childrenOfType(c, JSplitPane.class));
  if (sp != null)
    onFirstResize(sp, r {
      ifdef setSplitPaneOnFirstShowing_debug
        printVars setSplitPaneOnFirstShowing(+c, +value, size := c.getSize());
      endifdef
      if (delay == 0)
        sp.setDividerLocation(value);
      else awtLater(delay, r {
        sp.setDividerLocation(value);
      });
    });
  ret sp;
}

Began life as a copy of #1007235