_Added in 1.9.0_

*<notextile>on <level>:OPEN:<?|=|!|*>:<matchtext>:<commands></notextile>*
*<notextile>on <level>:OPEN:<?|=|!|*>:<commands></notextile>*

_For DCC Chat windows, the <matchtext> parameter is excluded, and it triggers only on successful connection._

Trigger for various events relating to the opening of a window of different types of windows.

Note: If you halt an [[on OPEN]] event triggered by an incoming private message, no [[on TEXT]]/[[on ACTION]] events is triggered

_See also [[on CLOSE]]._

_Haltable using ^_

*Parameters*

<level> - The [[User Access Level]] for the event to trigger.
<?|@|=|!|*> - The [[Matchtarget]] to listen to.
<matchtext> - The [[Matchtext]] to listen to.
<commands> - The commands to be performed when the event listener's criteria is met.

*Example*

<pre>
; Print a message when a query window is opened.
on *:OPEN:?:*:echo -ag Opened query window for $nick
</pre>