You can use “Set Word to Find/Replace” commands to pick up a selection, no matter if it’s multi-line.

@Yutaka ,

** But these 2 commands do not work as expected when “Find/Replace” dialog is open:
In “Find/Replace” dialog, the current string does not change correspondingly, though the picked string is already at the top of the history dropdown.

+ Suggestion 1:
Make these 2 commands also work for “Find/Replace in Files” dialog.

+ Suggestion 2:
Add “selection” in the descriptions for these 2 commands:
Sets the current word (or selection) as the find/replace string.