Disabled tabs have a pure blue background in CodeBlocks

I've been researching for a bit, and looks like (unsurprisingly) Code::Blocks uses the wxWidgets library.

More specifically, it makes use of the `wxAuiNotebook` widget, part of the wxAui sub-library, for displaying movable/stackable tabs and panels.

Then there's `wxAuiTabArt`, a base class for providing various pluggable back-ends/sub-classes.
Code::Blocks makes use of the `wxAuiDefaultTabArt` back-end for drawing the tabs, which gives that characteristic wxWidgets-y feel to the application... and in the case of ReactOS, a nice `#0000ff` color in the lower part of the disabled tabs surface.

That's where the problematic interfacing code resides. I'll keep investigating.

References:
http://wiki.wxwidgets.org/WxAUI
http://docs.wxwidgets.org/trunk/classwx_aui_notebook.html
http://docs.wxwidgets.org/trunk/classwx_aui_tab_art.html
http://docs.wxwidgets.org/trunk/classwx_aui_default_tab_art.html

CodeBlocks main window source code, search for `wxAuiTabArt`:
http://svn.code.sf.net/p/codeblocks/code/trunk/src/src/main.cpp

Here's the culprit, the code that draws the background tab gradient when disabled. I've yet to see from where that coloring comes from:
https://github.com/wxWidgets/wxWidgets/blob/c7f1a920b1aeaa6760da4c99fd533ee01d5081b8/src/aui/tabart.cpp#L451

Here's the Windows implementation of `GradientFillLinear`. Something's fishy over there, I don't like the way they calc the vertices' indexes:
https://github.com/wxWidgets/wxWidgets/blob/df13791078f107edda80f50f1ab498ad936ff069/src/msw/dc.cpp#L2844