This ensures the panel stays visible while applet alternatives dialog is open.
It also works around a quirk in Plasma Dialog which won't show if visualParent is in a auto-hidden panel.

BUG: 347855
BUG: 352459

Opened applet alternatives for TM in auto hidden panel, alternatives showed up and kept panel open. Panel auto-hid again once closed. Before the alternative dialog wouldn't even show up.

You get a brief flicker of the panel starting to hide while the QML is being processed but it's an improvement over the status quo in any way.

I tried to figure out why Dialog behaves weird (if I didn't set visualParent to alternativesHelper.applet which is in an auto-hidden panel it worked) but I got lost in there. I know that the dialog's position was properly determined but then somewhere it got confused.

Also verified that when I opened Alternatives for multipple applets simultaneously, the panel would only hide again after I closed the last one.

Some sneaky RAII in side ;)