To edit multiple selected objects in WebOffice core-client, some settings in IIS and Tomcat have to be configured.
Step 1:
Stop Apache Tomcat.
Step 2:
Open the file "server.xml" in the directory "C:\Tomcat\conf\". Add "packetSize=65536" in the line "<Connector port = "8009">". If the parameter "packetSize" is already existing, change it to 65536.

Step 3:
•Open the file "web.config" in the directory "c:\inetpub\wwwroot\"
•Add <httpRuntime maxUrlLength="16384" maxQueryStringLength="16384" /> in <system.web> as seen in the screenshot below.
•Add <requestLimits maxUrl="65536" maxQueryString="65536" /> in <system.webServer> -> "<security> -> <requestfiltering> as seen in the screenshot below.

Note: You can set the values of maxUrl, maxQueryString and packetSize higher or lower. Please be aware to use 2^n-Values.
Note: For uploading bigger files you can set the parameter maxAllowedContentLength at the <requestLimits> higher. The default value is 30000000, which is about 28.6MB.