The focus follows mouse function, alternates at high speed between an old and a newly created script tab.
Rkward 0.6.1 (from download.opensuse.org/repositories/devel:/languages:/R:/Supplement)
Opensuse 12.3
KDE 4.10.5 R1
Steps
2b may also explain the issue when using the "create" icon, as this places the cursor effectively within the text area.
Workaround
Deactive and use KDE's focus follow option,
(configure desktop > windows behavior > tab focus > Policy)
Notes
BTW, at times the rwkard mouse focus option isn't practical, e.g. when creating a new graphic output window, it gets pushed back. A delay could help, but wouldn't solve everything.
FYI
Many thanks for reporting, and very sorry about the long silence.
This issue should now be fixed in our development version (also the issue of pushing back plot windows). See https://rkward.kde.org/RKWard_Source_Repository for instructions on testing the development version, if you like.
Regards
Thomas