I could\'nt find a solution to a problem that has been hindering the use of notepad++.
When you double click text to highlight that text and others like it,
Notepad++ rely on Scintilla for word selection. As caoanan noticed in his answer, Scintilla can be configured with the SCI_SETWORDCHARS variable. You can set this variable in Notepad++ with a simple NppExec script:
Plugins -> plugin Manager -> Show Plugin Manager
Create the script
Plugins -> NppExec -> Execute ...
write this code (you can add other characters, like .$#@ at the end of the list):
NPP_CONSOLE 0
sci_sendmsg SCI_SETWORDCHARS 0 "CDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-"
Plugins -> NppExec -> Advanced Options...