Fix the bug with the usage of `_filter = $("#"+$.jgrid.jqID(fid))` before the form will be created. The current implamentation uses empty `_filter` inside of `showFilter` at the first call.
Fix the bug with the usage of `_filter = $("#"+$.jgrid.jqID(fid))` before the form will be created.
The current implamentation uses empty `_filter` inside of `showFilter` at the first call.

Signed-off-by: Dr. Oleg Kiriljuk <4aa8e7d3b0b3361976c5ce583d813bfa9d7af3cb@ok-soft-gmbh.com>

javapark/jqgrid