I want to read/search in an XML document in a window of a wxPython application.
A lot of text editors will highlight the content and maybe have support for
block and unblock of XML elements.
Is there a component that provides at this sort of functionality in wxPython?
Take a look at the wxPython demo of the StyledTextCtrl. It's in wx.stc. Anyway, the demo labeled StyledTextCtrl_2 shows how to create syntax highlighting for a Python file using self.SetLexer(stc.STC_LEX_PYTHON). 
For XML, you would just need to change that line to self.SetLexer(stc.STC_LEX_XML). You should also look at PyShell / PyCrust or possibly Editra. The latter is a text editor created with wxPython that does this sort of thing.
How should I display an XML document in a wxPython UI?