That's a ridiculous set up, but OK...
So how do you want it to work, exactly? Do you want the Advanced Search window to open and search the current file with the selected value in the drop-down the moment it's selected?
That is correct. It would be great if possible. Thanks for your time
OK, then in that case you can use this code as the drop-down's custom validation script (just make sure to tick the option to commit the selected value immediately, under the field's Properties - Options tab):
Awesome! That should do the trick. Would it be to much work to have a button call the command?
No, that's easily done. Let's say the name of the drop-down is "Dropdown1". Just use this code as the Mouse Up event of your button: