Unable to replicate error myself, but fix for https://bugs.gentoo.org/792204
from https://github.com/projectM-visualizer/projectm/issues/449
diff '--color=auto' -ru a/src/projectM-qt/qprojectmwidget.hpp b/src/projectM-qt/qprojectmwidget.hpp
--- a/src/projectM-qt/qprojectmwidget.hpp	2024-06-26 10:48:30.825008203 -0000
+++ b/src/projectM-qt/qprojectmwidget.hpp	2024-06-26 10:49:03.265800570 -0000
@@ -23,6 +23,7 @@
 #define QPROJECTM_WIDGET_HPP
 
 #include <iostream>
+#include <GL/gl.h>
 #include "qprojectm.hpp"
 #include <QGLWidget>
 #include <QMutex>
