notepad++ user defined regions with folding

For version 6.5.5 and above:

Under the menu "Language" there is a menuitem called "Define your language..."

In the tab "Folder & Default" is a group called "Folding in code" where you can enter an "Open"- and a "Close"-Keyword.

For versions older than 6.5.5:

Under the menu "View" there is a menuitem called "User-Defined Dialog..."

In the tab "Folder & Default" you can enter a "Folder Open Keyword" and a "Folder Close Keyword"

Another simple way is just to add a comment marker followed by open-block to begin a block, and a comment marker followed by end-block to end a block. In C, C++, Java, Javascript, etc. it would look like this:

//{

//}

I have a similar problem. I want to add a custom tag like #region / #endregion to create arbitrary folding points in languages that don't support it. Specifically, I am trying to do this for php.

After researching for an hour or two, it seems that modifying an existing language is quite difficult due to the underlying scintilla lexer, and writing a plugin may be the only way to accomplish this.

I did discover however a decent workaround:

Wrap the code you wish to fold in comments like:

#{ 
...
#}

Then move your cursor before the open brace and press CTRL+ALT+b to highlight the entire block, followed by ALT+h to hide it.

It's a different operation than folding, but it works in a pinch.

I used Marcelo's answer to solve this for myself (in Perl), with one change...
If I included a space between the comment symbol and the bracket then it wouldn't work. It had to be placed immediately after:

#START example
################{

print "Hi there! ";
print "How are you?\n";

#}END example

Note that if I do:

#END example }

with the bracket after the text it won't work either