From 619742f70f004ae7c876beb74a57113ff8b34173 Mon Sep 17 00:00:00 2001
From: krcroft <krcroft@users.noreply.github.com>
Date: Sat, 28 Mar 2020 20:42:17 -0700
Subject: [PATCH] Improve comment about EXPOSED event

---
 src/gui/sdlmain.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/gui/sdlmain.cpp b/src/gui/sdlmain.cpp
index 2d036b89..ab88feaf 100644
--- a/src/gui/sdlmain.cpp
+++ b/src/gui/sdlmain.cpp
@@ -2208,7 +2208,14 @@ void GFX_Events() {
 				case SDL_WINDOWEVENT_RESIZED:
 					GFX_HandleVideoResize(event.window.data1, event.window.data2);
 					continue;
-				// window has been exposed and needs to be redrawn
+				/*
+				 *  EXPOSED indicates that the window needs to be redrawn.
+				 *  Note that on Windows/Linux-X11/Wayland/macOS, the EXPOSED event
+				 *  is fired after toggling between full vs windowed modes. However this is
+				 *  never fired on the Raspberry Pi (when rendering to the Framebuffer);
+				 *  therefore we rely on the FOCUS_GAINED event to catch window startup
+				 *  and size toggles.
+				 */ 
 				case SDL_WINDOWEVENT_EXPOSED:
 					if (sdl.draw.callback)
 						sdl.draw.callback(GFX_CallBackRedraw);