Ridge, you can patch it yourself. I can't check 13.12, but the XRS should be similar.
Go to the folder where CB is installed, then go to share/Codeblocks, open resources.zip and change env_settings.xrc adding the <style>wxDEFAULT_DIALOG_STYLE|wxRESIZE_BORDER</style> line, so it looks like this.
<?xml version="1.0" encoding="utf-8" ?>
<resource xmlns="http://www.wxwidgets.org/wxxrc" version="2.5.3.0">
<object class="wxScrollingDialog" name="dlgEnvironmentSettings">
<title>Environment settings</title>
<centered>1</centered>
<style>wxDEFAULT_DIALOG_STYLE|wxRESIZE_BORDER</style>
<object class="wxBoxSizer">
<orient>wxVERTICAL</orient>
...