Various fixes

resources/shaders/110/mm_contour.fs

@@ -1,13 +1,8 @@
 #version 110
 
-const float EPSILON = 0.0001;
-
 uniform vec4 uniform_color;
 
 void main()
 {
     gl_FragColor = uniform_color;
-    // Values inside depth buffer for fragments of the contour of a selected area are offset
-    // by small epsilon to solve z-fighting between painted triangles and contour lines.
-    gl_FragDepth = gl_FragCoord.z - EPSILON;
 }