Thanks for prompt reply, Venu. I have type="visibleGroup" already:
<container colcount="2" img="cus:logo16x16.png" label="myLabel" name="myName" type="visibleGroup" visibleIf="[/tmp/@folderId]==12345">
Unfortunately my container doesn't appear regardless the folder id. I changed to "!=" for testing, but the result is the same - I can't see my container. Maybe I have to add some code in order to load/reload folder id?