Splitpane with HtmlPane Resize Problem

SmartGWT Pro 5 rom 14. August 2015
Browsers: all

We have Splitpane:
- navi pane: contains a list (not important for this case)
- line pane contains Html pane
- detail pane contains simple label (not important for this case)

The problem ist that we can make the list pane bigger and bigger and we see the website (html) in int.

But we cannot make the list pane smaller again.

It also happens with SmartGwt 4.1 Pro.

Thx for your ideas