We seem to have a collection of related problems here. CustomURL was mostly designed to handle the simple case of generating links to detail pages or reports using key fields. Obviously, people find this useful enough that there are lot of different scenarios being tried.

Some problems I've seen are

  attach javascript to a field (this is tricky, since you have to guarantee the script will work on all pages)
  custom url with path substitution
  custom url with conditional substitution

Then there is the problem of the difference between the Ext.Grid and the DataRegion (bigger issue)

We can tackle some of these problems from different angles.

1) add incrementally richer custom url functionality (expressions, etc).
2) expand the DataRegion object to make it easier to 'post-process' the grid to modify the url/javascript properties (very general solution, and can be page/application specific)
3) full Ext.Template like definition of the column rendering (easy to mess up the whole page through)

In this particular case you could link to an intermediate page instead of directly to executeQuery. I we need to talk about other approaches here.