* use it in MetadataListView and GraphEditor 'add Node' menu
* GraphEditor: forward MenuItem key events to searchBar to be able to continue editing the filter even if it lost active focus
* bugfix: in latest PySide2 versions, application palette is not properly applied to all QtQuick Controls 2 components. Force this by exposing QApplication palette and bind it to the root ApplicationWindow.
* rename all "palette" ids to "activePalette" to avoid clashes with "palette" property on QtQuick Controls 2
* use parent component palette when it makes sense to propagate active/disabled style (instead of always using Active SystemPalette)
* display selectable-by-mouse source filepath
* add radius property to FloatingPane to control border radius from outside
* use FloatingPane in ImageMetadataView
* use variant for filterValue and implement different logics to test filter matching based on value type
* allow redefinition of modelData and respectFilter functions to customize logic from outisde if need be
* add convenient 'reverseSortOrder' method
