1. When Extesible Style Sheet is created using the 
Template in the XML module and the newly created XSL is 
validated using the "Validate XML" action, one will get 
the following errors:

General Schema Error: Grammar with uri 2: 
http://www.w3.org/1999/XSL/Transform , can not found. [13] 
Element type "xsl:stylesheet" must be declared. [13] 
Element type "xsl:strip-space" must be declared. [15] 
Element type "xsl:preserve-space" must be declared. [17] 
Element type "xsl:template" must be declared. [20] 
Element type "xsl:apply-templates" must be declared. [21] 

Better namespace support will probably fix this.

2. Code completion and syntax highlighting should be 
available for XSL files.

3. XPath builder where one could pick XPaths from source 
XMLs would be nice to have.