You can use autocomplete feature to use fulltext searching in some field.
Check demo/integration/autocomplete.php

Currently, external page linking demo is not available, but it seems doable too.

Abu,

Yes, It is very nice to use autocomplete feature with fulltext searching in some field. I have just started to use it.

Why I asked this question to you ; If it can be possible that if I can open Customer.php (external customers page) in edit and add dialog form , If customer does not exits in customers than I can easly add a new customer just clicking add button of customer page. And then return first page and choose new customer in related field input.

Regards…

What i can recommend in such case is, make a custom toolbar button (refer demo/appearence/toolbar-button.php) and disable default edit option of grid.

In that custom toolbar button, you can open a modal window (demo/integration/fancy-box.php) with the URL of your new page.
I've not tested this scenario but i hope it help.

Abu,

Yes, I will refer and try to use (demo/appearence/toolbar-button.php) and
(demo/integration/fancy-box.php).

Thank you.