Weird KDE/QT clipboard behavior?

[Hongli Lai <h lai chello nl>]

I'm trying to write a clipboard daemon for GNOME that keeps the contents of 
the clipboard in memory even after an app has already closed. I noticed that 
my daemon breaks KDE apps.

Upon investigation, I found out that the TARGETS atom set by KDE apps appears 
to be invalid. I use the GTK+ function gtk_selection_data_get_targets(), 
which retrieves a list of atoms from the clipboard owner by reading the 
TARGETS atom. This function checks for the following things:
- The selection data's length is greater than 0.
- The format is 32.
- The selection type is of type ATOM (4).
This last check fails. The TARGETS atom set by KDE apps is named "TARGETS", 
but it's numbered 92, not 4.
I tried to force the type to GDK_SELECTION_TYPE_ATOM (4). The function 
succeeded, but the resulted list contains mostly invalid atoms. The *only* 
valid atom in that list is the atom STRING.
After more investigation, I found that KDE apps do set a UTF8_STRING atom, but 
that atom doesn't appear in the list of TARGETS.

I also just noticed that when I copy some text in KMail (or any other KDE 
app), and rightclick on a text entry in a GTK+ 2 app, the Paste menu is 
disabled (because gtk_selection_data_get_targets() returns FALSE). But the 
pasting *does* work, because if I press Ctrl+V, the copied text pastes just 
fine. COMPOUND_TEXT and UTF8_STRING are set correctly by KDE apps, but they 
just don't appear in the list of TARGETS.

Is there a reason why TARGETS appears to be invalid? Am I doing something 
wrong or is the KDE clipboard a little broken?