When you right click on a node at Project explorer,
if it is a html, htm or jsp, the pop-up menu would give you the opportunity to 
run/debug a file. If it is an xml file, the menu would allow you the 
opportunity to Check/Validate XML, Generate DTD, etc.

What project explorer does not but should perform is read servlet mappings 
from web.xml. e.g., the following servlet mapping in the web.xml mapping any 
laszlo XML files to LPS.

    <servlet-mapping>
        <servlet-name>LPS</servlet-name>
        <url-pattern>*.lzx</url-pattern>
    </servlet-mapping>

Therefore, right-clicking a .lzx file at projects explorer should have pop-up 
menu show both the xml file manipulation as well as run/debug file. Where the 
the servlet to run/debugged is the servlet pointed to by LPS.

On the other hand, we have to admit that *.lzx is merely a URL pattern to be 
caught and redirected to LPS and has nothing whatsoever to do with any file of 
that pattern located within the web folder. That it is up to LPS servlet to 
resolve that pattern to any file it wishes.

Perhaps then, let the user have an opportunity to config the pop-up menu. When 
I opened up Tools ---> Advanced Options -> Object Types -> [XML Objects or JSP 
Objects, etc] -> Actions, I could see actions corresponding to the respective 
types. In particular "Filesystem action", which I presume resolves to whether 
to allow the pop-up to give us an opportunity to validate/run/debug the file 
(as resolved by some kind of mime resolver).

This alternative suggestion, which might be more amenable, is to allow me to 
config Filesystem actions so that I could add in run/debug action for *.lzx 
files.

Then, of course, you might persuade me to construct a html file to launch any 
URLs with a leaf pattern of .lzx - an avoidance which prompted me to put in 
this suggestion in the first place.