I started new session and switch to another user after return I find this

Why the screen became like that ? my distro is Kubuntu 16.04

userkde wrote:Why the screen became like that ? my distro is Kubuntu 16.04

Without any error messages it is hard to say - application seems to be 'NetBeans' - doing a search with: 'netbeans missing text with plasma5'
A hit: https://netbeans.org/bugzilla/show_bug.cgi?id=135753
It is older and with the the Windows 7. But you could look what information is asked at the bug report and dig those up.