windows of one application spreading to other workspaces

[startx <startx plentyfact org>]

hello.

i recently came across a problem when using an application
which opens some kind of notification window: 

as an example: if i use claws-mail (a gtk email client) to receive
my emails and - after clicking the "check mails button" - switch
to another workspace while claws-mail is contacting the server,
a possible notification from claws-mail (e.g. a server error)
is opened on the _new_ workspace. however i wont see this 
because there is no application panel and its hidden "behind" 
the open window.

when i then switch back to the workspacewhere claws-mail is open
it seems to be frozen (as its waiting for me to react to the
notification on another workspace)

here i wonder: should an application not only use _the same_ workspace
to open other windows instead of trying to "follow me"? is this
behaviour given by the windowmanager or the application?

hope my description is not too confusing,

startx