I was using the latest stable release r168. Just tested r169... the problem is reversed... in r169 when you turn the device from portrait to landscape... its aligned properly at the top, but the bottom of the canvas is about 10-20 pixels below the screen. So instead of it appearing to push canvas up 10-20 pixels cropping the top off screen... in r169... the size of the canvas appears to be 10-20 pixels taller in height than the screen. Those 10-20 pixels are off screen. This was tested on an ipad mini running 7.1. Reminder... this issue cannot be replicated in emulators.
Not sure this is related, but just in case... I get this error when opening my file in r169...
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Construct 2 Check failure
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Check failure! This is probably a bug:
Plugin of non-world type specified 'rotatable'
Condition: !(plugin_type == era::pt_objecttype && rotatable)
File: Projects\ObjectType.cpp
Line: 37
Function: __cdecl ObjectType::ObjectType(class Project &,class ObjectFolder &,class Plugin *,const class std::basic_string<wchar_t,struct std::char_traits<wchar_t>,class std::allocator<wchar_t> > &,unsigned __int64)
Build: release 169 (64-bit) checked
Component: Construct 2 IDE
(Last Win32 error: 0)