CodeEditor highlighting broken with wxPython

Description

Using the wxPython backend, the CodeEditor highlighting does not work as expected. In particular, only some of the lines are being highlighted. See the following video:

Video0.mp4

The video is generated from the following code: https://github.com/greschd/traitsui_code_editor_syntax_highlighting_issue/blob/main/code_editor_test.py

In particular, only selected lines appear to be highlighted, depending on which line was last edited.

Additional context

I can get the syntax highlighting to appear correctly by removing the following lines:

traitsui/traitsui/wx/code_editor.py

Lines 354 to 356 in ce8b285

    
           else: 
        
               self.control.StartStyling(position) 
        
               self.control.SetStyling(style_length, stc.STC_STYLE_DEFAULT)

However, I'm not familiar enough with wx.stc highlighting to know if this might be the correct solution, or what else this might break. I have not tested this in combination with the options selected_line, dim_lines, etc..

Environment

Tested on the following environments, with the same behavior everywhere:

OS: Windows 11
- Python 3.9
  - wxPython 4.1.1
  - wxPython 4.2.0
- Python 3.10
  - wxPython 4.2.0
OS: Ubuntu 20.04 on WSL2
- Python 3.8
  - wxPython 4.2.0

	else:
	self.control.StartStyling(position)
	self.control.SetStyling(style_length, stc.STC_STYLE_DEFAULT)