Category and Sub Category Mantis 1.1.6

[swingkid]

Is there a way to to link two fields together such as Category and Sub-Category so that
if I select Category A, then when I try and select a sub-category it is a drop down box of A-1, A-2, A-3 etc..
If I select a Category B, then when I try to select a sub-category it is a drop down box of B-1, B-2, B-3 etc...
Instead of a huge list of A-1, A-2, A-3, B-1, B-2, B-3.