After spending some investigations:
12.1X46-D10.2 with Cluster Modus active, has problems editing security policies with application.
No mather what browser..
12.1X46-D10.2 without Cluster Modus working fine.
Downgrad to junos-srxsme-12.1X45-D15.5-domestic solved my problem with the cluster.
Maybe someone on Jtac can spend some time on producing the error.
PM also welcome