The GameWindow right now is the exact same screen as on the device – you can switch through different popular screen resolutions by pressing the keys 1-6. For example you can test how the game will look like on an iPhone3GS, iPhone4, iPad, etc. directly while running the game. Here is a list which resolutions are set when pressing the different keys: http://doc.felgo.com/beta/qml-components-vplay1-gamewindow.html
Scrolling is already supported – you can use a Flickable element for that. We are also working on a side scrolling demo which we will release with the source code and a tutorial to demonstrates its usage in more detail.
Great you mention the particle editor, as it is the first editor we are currently building with the LevelEditor API 🙂 It will be available in one of the next releases, and allows to modify the particle properties at runtime and see their effects. Like with the level editor, it is also usable on the device so you can test the performance impact of changing textures and properties directly on your target hardware.
Regarding parenting: this is an essential feature which QML and the scene graph we are using are built upon: the children will always stay relative to the parent – so when you move a parent, all the children move as well. So if you write something like the following:
Then the image will also be placed at 40/10 relative to the parent.
Thanks for your feature requests – if you would find anything else helpful please let us know.