TreeViewer Bugs on Android and iOS

Hello Tabris team,
on playing around with the TreeViewer element I have found 3 bugs. 1 on iOS, 1 on Android and 1 on both sides.

Tested with: iOS11, iOS10 and Android 6.0.1

I have created a TreeViewer with the flags 'SWT.SINGLE' and 'SWT.V_SCROLL. The content provider implements 'ITreeContentProvider'.

**iOS**
After "clicking" on an element with childs, the "child view" is no longer scrollable which makes it unusable, because one can not reach/see every child element. Only the "root node view" is scrollable. This does not occur on Android.

**Android**
After clicking on a child element, no "back" button is created like in iOS, so it has to be created manually. Additionally elements which have child elements are not automatically marked (e.g. with an arrow like on iOS), so this has to be implemented manually too. This means that on writing a code for both devices one always have to implement a "device switch".

**Both**
If an element is selected which does not have any childs, this element keeps selected. No flag or something else changes that behaviour.