Use explicit shader attributes.

glsl/rgba.vert

@@ -1,9 +1,13 @@
 uniform vec2 Scroll;
 uniform vec2 r1, r2;
 
+attribute vec4 aVertexPosition;
+attribute vec4 aVertexTexCoord;
+varying vec4 vTexCoord;
+
 void main()
 {
-	vec2 p = (gl_Vertex.xy - Scroll.xy)*r1 + r2;
+	vec2 p = (aVertexPosition.xy - Scroll.xy)*r1 + r2;
 	gl_Position = vec4(p.x,p.y,0,1);
-	gl_TexCoord[0]  = gl_MultiTexCoord0;
+	vTexCoord = aVertexTexCoord;
 }