There is a mechanism to customize Unicode window checking (i.e. the use of the Action menu items Execute ⌘R, Check syntax ^⌘R and Validate ⌥⌘R):

• If you want to handle the checking of the files of extension .zzz, you have to define in Smile's context a handler named checksyntaxEXT and/or validateEXT and/or executeEXT (replace EXT with the extension you are interested in).
  Those handlers are called respectively when the user press ^⌘R, ⌥⌘R or ⌘R. It has one parameter that is the window reference.
• If the file extension is not handled but the contents is an xml (for example, in the case of a .xml file extension), you can define handlers specific to the tag name of the root element: you have to define in Smile's context a handler named checksyntaxxmlTAG and/or validatexmlTAG and/or executexmlTAG (replace TAG with the tag name of the root element you are interested in).
• If this handler does not exists or if it fails, the default behavior occurs.
• You can have such handlers defined in your context additions.