<fxlayout>

  <page name="Adjust Levels">

<separator label="RGB"/>

    <control>in_rgb</control>

    <control>out_rgb</control>

<separator label="Red"/>

    <control>in_r</control>

    <control>out_r</control>

<separator label="Green"/>

    <control>in_g</control>

    <control>out_g</control>

<separator label="Blue"/>

    <control>in_b</control>

    <control>out_b</control>

<separator label="Alpha"/>

    <control>in_m</control>

    <control>out_m</control>

  </page>

  <page name="Gamma">

    <histogram/>

    <control>gamma_rgb</control>

    <control>gamma_r</control>

    <control>gamma_g</control>

    <control>gamma_b</control>

    <control>gamma_m</control>

  </page>

</fxlayout>