Not sure about the resize issue, but from your screenshot it looks like it has a bunch of code all on one line. Geany/Scintilla is notoriously slow with extremely long lines, especially when line wrapping is enabled.

Aside from trying to disable line-wrapping, there's a couple things you can possibly do if you control whatever generated that code. If you are using C++11 or later you can use [raw string literals](https://en.cppreference.com/w/cpp/language/string_literal) or if not use plain C-style string literal concatenation (described on same link). Both would allow to split the generated code onto multiple lines which should help with the Geany performance issue as well as to make the generated code more readable.

You could try running Geany from the command line with the `-p`/`--no-plugins` option. It's possible that whatever debugger plugin you have loaded is not designed to fit in the message window area when it's on the right like you have it. If it doesn't happen when no plugins are loaded, try and run it normally again but change the preference to put the message window back in the bottom to see if that's what's going on.

codebrainz: I will test tomorrow (too drunk at the moment... :) elextr:Fedora 32 (Workstation Edition) uname: 5.7.11-200.fc32.x86_64 #1 SMP Wed Jul 29 17:15:52 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Ok trapped, its this: 

disabled it and now works ok.

Also changing layout as below works.