Hello,
first off: With the hints given, this lead me to the correct solution. You find this below the =====. I tell the complete story here for letting you know the (boring) details. (But I still can’t understand everything - see below)
but you could help people in helping you by at least tell which level of openSUSE and which level of KDE you use.
ooops, sorry, stupid me - surely you need to know this:
Suse 11.2 (64 Bit), patched up to date
KDE 4.3.5
I may have accidentally stumbled across something just this morning while trying to get system sounds to work that may help. In the CONFIGURE DESKTOP (Personal setting) app there an option to configure DEFAULT APPLICATIONS.
I tried this, here is my result:
I changed this to firefox (I’ve installed 3.6 from Mozilla binary tar-ball)
If I now do the same thing in Inkscape, firefox offers to download (!) the following file:
file:///var/tmp/kdecache-jost/krun/6484.0.index.php
There are no multiple startups (better), but I still don’t get to see the contents either (still bad) 
So I tried to configure this back to konqueror (just as a test).
If I click the …] button, I get the list like in the K-menu. If I choose Internet/Web-Browser/konqueror I got an entry named “konqbrowser”. If I use this and try it in inkscape again, I get a pop up: (my translation below, I failed to have inkscape start with english GUI, using > export KDE_LANG=“en_US”;inkscape)
“Die Datei /var/tmp/kdecache-jost/krun/6607.0.index.php ist als UTF-8 kodiert geöffnet worden, enthält aber ungültige Zeichen. Der Zugriff ist auf Nur-Lesen gesetzt worden, da ein Speichern den Inhalt der Datei zerstören könnte. Öffnen Sie die Datei erneut mit der korrekten Kodierung oder deaktivieren Sie den Nur-Lesen-Modus über das Menü.”
“The file var/tmp/kdecache-jost/krun/6607.0.index.php has been opened as UTF-8 coded, but contains invalid characters. The access has been set to read-only, because saving could destroy the contents of the file. Open the file again using the correct coding or deactivate the read-only-mode using the menu”
On clicking ok, just the source-text is opened (so similar to firefox)
But - tata - here is the “trick”:
I choose (again my translation) K-menu/programs/system configuration
There “Standard components”; “Web Browser”
I entered (by hand) “konqueror” in the line and applied the setting.
And now konqueror starts (just once
and displays the wanted help page. (on Inkscape)
My problem is, I now have no clue, what has been wrong in the first place. At least I didn’t see anything suspect in the menu when I opened it the first time.
(There is some small “chance” that I get the problem again: I have rarely seen strange things happening, depending on hibernate/suspend usage before)
Thanks for pointing me in the right direction - one really bad annoyance solved !
Martin