Redmine

I desperately need the custom field for issue lining.
Example: I have one tracker named "Customers". Another tracker called "Jobs" (currently we're using this in our production).
What I need is to link job with the customer. I know it can be done by ticket relations but it's not exactly what I need.
If there will be some possibility of filtering, it can be really nice (like show only tickets from this project / this tracker).

I can write more detailed documentation for this.
We can even pay for development of this functionality.
Thanx :)

• How to make a list of possible tickets filterable: Just create the custom query. In the configuration of the custom field, a user can select custom query (Select or just enter custom query's id) which will filter out possible values.
• Which UI element to use: I have two ideas: Select, for shorter lists and Whisperer for longer lists.

Inter-linking of issues will really move Redmine a lot for other non-sw development projects, like asset/job tracking, etc.