InDesign CC 2014.1 (InDesign version 10.1) and its corresponding plug-in SDK (x070 and x071) contains a new include which will be of particular interest to anyone developing hybrid extensions.
In case you don’t know, a hybrid extension is an extension which consists of one or more native plug-ins and one or more HTML (or Flash) extensions.
The new APIs, found in the SDK at /source/public/interfaces/ui/ICSXSPlugPlugExtensions.h, enable workflows where a native plug-in needs to open or close an extension.
Whilst there is no need to port or recompile your plug-ins from 10.0 to be compatible with 10.1, if you want to use this API you will need to use the latest SDK to pick up the new header and you will then have to recompile.
The InDesign update you received in August 2013 (InDesign 9.1) included the enabling of HTML5 extensions.
As you may already know, starting in the middle of 2014 Adobe will begin removing Flash-based extension support in Creative Cloud products, starting with Photoshop CC.
If you have any hybrid or regular Flash extensions for InDesign you need to begin migrating them to HTML5 as soon as possible.
InDesign user-interface development can be expensive. It takes a lot of effort to implement a dialog or panel in ODFRC. Things should improve in future versions, with the possibility of using Flash-based user-interface tools like Flex and FlexBuilder. While this represents the future direction of InDesign user-interface development, there is a present reality in InDesign CS4. With an understanding of the current situation, you can implement Flash-based user-interfaces for InDesign CS4.