reduced required GLSL version to 1.2

src/glrectangle.cpp

     our = ur + glm::vec2(border,border);
     obr = br + glm::vec2(border,-border);
     generateBuffers();
-    std::string vert = "#version 130\n in vec2 position;\n uniform mat4 projection;\n void main() {\n gl_Position = projection*vec4(position,0,1);\n }";
-    std::string frag = "#version 130\n uniform vec4 color;\n out vec4 outColor;\n void main() {\n outColor = color;\n }";
+    std::string vert = "#version 120\nattribute vec2 position;\nuniform mat4 projection;\nvoid main() {\ngl_Position = projection*vec4(position,0,1);\n}";
+    std::string frag = "#version 120\nuniform vec4 color;\nvoid main() {\ngl_FragColor = color;\n}";
 
     shader = new Shader( vert, frag, false );
 }

src/slop.cpp

 slop::SlopSelection slop::GLSlopSelect( slop::SlopOptions* options, bool* cancelled, SlopWindow* window ) {
     slop::mouse = new slop::Mouse( x11, options->nodecorations, window->window );
 
-    std::string vert = "#version 130\nattribute vec2 position;\nattribute vec2 uv;\nvarying vec2 uvCoord;\nvoid main()\n{\nuvCoord = uv;\ngl_Position = vec4(position,0,1);\n}\n";
-    std::string frag = "#version 130\n uniform sampler2D texture;\n varying vec2 uvCoord;\n out vec4 outColor;\n void main()\n {\n outColor = texture2D( texture, uvCoord );\n }\n";
+    std::string vert = "#version 120\nattribute vec2 position;\nattribute vec2 uv;\nvarying vec2 uvCoord;\nvoid main()\n{\nuvCoord = uv;\ngl_Position = vec4(position,0,1);\n}\n";
+    std::string frag = "#version 120\nuniform sampler2D texture;\nvarying vec2 uvCoord;\nvoid main()\n {\ngl_FragColor = texture2D( texture, uvCoord );\n}\n";
     slop::Shader* textured = new slop::Shader( vert, frag, false );
     std::vector<slop::Shader*> shaders;
     for( int i=0;i<options->shaders.size();i++ ) {