Horizon EDA: Fix Intel GPU redraw issue

overlays/default.nix

@@ -2,5 +2,6 @@
 {
     imports = [
         ./burp.nix
+        ./horizon-eda.nix
     ];
 }

overlays/horizon-eda.nix

@@ -0,0 +1,13 @@
+{ config, ... }:
+{
+    nixpkgs.overlays = [
+        (self: super: {
+            horizon-eda = (super.horizon-eda.overrideAttrs (old: {
+                # Add an environment variable to fix redraw issues on Intel Graphics
+                patches = [
+                    ./horizon_software_draw_surface.patch
+                ];
+            }));
+        })
+    ];
+}

overlays/horizon_software_draw_surface.patch

@@ -0,0 +1,10 @@
+diff --git a/org.horizon_eda.HorizonEDA.desktop b/org.horizon_eda.HorizonEDA.desktop
+index 7551df54..d8df7800 100644
+--- a/org.horizon_eda.HorizonEDA.desktop
++++ b/org.horizon_eda.HorizonEDA.desktop
+@@ -5,4 +5,4 @@ Categories=Development;Engineering;Electronics;
+ Type=Application
+ Terminal=false
+ Icon=org.horizon_eda.HorizonEDA
+-Exec=horizon-eda %U
++Exec=env GDK_GL=software-draw-surface horizon-eda %U