Bugs found with optimized FindAndReplace

[michael]

Just a list to keep track what needs to be fixed before we can merge #1064

• [ ] deactivating panel with ESC breaks
• [ ] when doing a second search, matches of previous search are not cleared
• [ ] when typing a new string that produces another match, it is one operation too late (e.g. when searching for xx and typing... it gets colored when typing "xxy" but not when typing "xx".
• [ ] breaking a paragraph with matches does not work