Construct 2 Release r189

Amazon Appstore exporter: now provides option to export packaged apps. Simply zip the resulting folder and you can submit an app hosted by the Amazon Appstore instead of your own server.

WebGL shader effects can now use a 'scrollPos' vec2, which is the scroll position (in the middle of the screen) in layout co-ordinates.

Sine behavior: reverted r188's fix to update the initial state when setting active, since it broke existing games. Instead there is a new 'Update initial state' action to do this explicitly.

The editor can now import 32-bit GIF files, but we still strongly recommend using PNG instead.

Form controls now respond better to changed browser zoom levels on desktop.

Destroying large numbers of instances in one go is now considerably faster. This could be a significant help if destroying entire sections of a layout at a time.