Shows how to use the Toggle material property drawer in a shader. See the reference manual for further details: http://docs.unity3d.com/ScriptReference/MaterialPropertyDrawer.html

ToggleTest.shader

Shader "ToggleTest"
{
    Properties
    {
        [Toggle(FILL_WITH_RED)]
        _FillWithRed ("Fill With Red", Float) = 0
    }
    SubShader
    {
        Pass
        {
            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag

            #pragma shader_feature FILL_WITH_RED

            #include "UnityCG.cginc"

            float4 vert(appdata_base v) : POSITION
            {
                return mul(UNITY_MATRIX_MVP, v.vertex);
            }

            half4 frag(float4 position : POSITION) : SV_Target
            {
            #ifdef FILL_WITH_RED
                return float4(1, 0, 0, 1);
            #else
                return (float4)1;
            #endif
            }

            ENDCG
        }
    }
}