Hi albehany, sorry I thought you were trying to use the script to do it which is here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=8064.8

With that way you leave the default SidePane.htm in place and put that script in MoI's appdata\startup folder so it runs on program startup.

For your editing the SidePane.htm one problem is that you've got duplicate ids here (on the lines marked with >>>>)

>>>>       <moi:PaletteHeader id="TransformTabContent">
                    <moi:TabContainer>
                        <moi:TabButton id="TransformTab" class="RightTabButton"><moi:Text textid="Transform tab"/></moi:TabButton>
                    </moi:TabContainer>
                </moi:PaletteHeader>
                <moi:PaletteBody>
>>>>             	<div id="TransformTabContent">

Both of those having the same id value will cause problems. Modify the top one to id="TransformHeader" instead.

The second problem is that the close tag for the construct <moi:PaletteBody> is missing, which makes the transform tab to be a child of construct.

So immediately above the transform tab add </moi:PaletteBody> so the construct one is closed.

That should get it working after those 2 fixes I think.

- Michael