I've published a package called FindAgain to the Cincom public Store 
repository.  It allows you to search for senders of a selector or 
references to a class or shared variable (which you could do before) and 
when you select one, find subsequent references to that selector or 
variable in the method (which you couldn't do before). The Code Tool's 
popup menu in the Browse Senders or Browse References windows will have 
two new menu items called Find Next and Find Previous. If there is more 
than one reference to the selector or variable in the method, Find Next 
will be enabled to allow you to find the next reference. Once you reach 
the last reference, Find Next is disabled.  Once you use Find Next, the 
Find Previous menu item will be available until you hit the first reference.

This code is released without restrictions and without warranty. Use it 
for whatever purpose you wish. If it doesn't work for you, fix it and 
publish your fixes.

Have fun