There were some excellent additions to the plug-in API with version 10 of Flare and this blog will touch on that in later posts. But I want to make a quick note about a change to the API that you may need to address if you built plug-ins for version 9 and are planning to use those in version 10.
In version 9, there was an ICustomToolstrip interface. Now there is an ICustomToolBar interface. This bothered me a little until I realized that although the change broke my version 9 plug-ins that used ICustomToolstrip, it eliminated a silly workaround I had to use to share code between buttons for custom toolstrips, now called custom toolbars and ribbon groups. Note that MadCap still refers to the classic UI as the Tool Strip (user) Interface.
Before there was AddToolStripButton(string, string, EventHandler). Now there is AddButton and it can use the same class that inherits ICommand as AddRibbonButton(string, ICommand, object, string, RibbonIconSize, string, string, string). This enables better code sharing for buttons on a toolbar and a ribbon group and eliminates the need for the EventHandler and silly path to share logic for the buttons that was necessary before. Dealing with toolbar buttons and buttons on ribbon groups is just a fact of life if you want to support both UI options in Flare.
In conclusion, I think a little bit of rework in existing plug-ins is a good thing in this case.