dawn: provide path to wish for the GUI

pkgs/applications/science/physics/dawn/default.nix

@@ -1,6 +1,8 @@
 { lib
 , stdenv
 , fetchurl
+, tk
+, makeWrapper
 }:
 
 stdenv.mkDerivation rec {
@@ -18,12 +20,19 @@ stdenv.mkDerivation rec {
       --replace 'INSTALL_DIR =' "INSTALL_DIR = $out/bin#"
   '';
 
+  nativeBuildInputs = [ makeWrapper ];
+
   dontConfigure = true;
 
   preInstall = ''
     mkdir -p "$out/bin"
   '';
 
+  postInstall = ''
+    wrapProgram "$out/bin/DAWN_GUI" \
+      --prefix PATH : ${lib.makeBinPath [ tk ]}
+  '';
+
   meta = with lib; {
     description = "A vectorized 3D PostScript processor with analytical hidden line/surface removal";
     license = licenses.unfree;