Show Desktop Button

What is "the first pixel of the button"?
How is your question related to the tweaker?

If you place the cursor to the end of the screen, the button is pressed, but it does not go to the desktop.
Do you see it?
Why is that?

Windows 7, classic theme?

Winows 7 x64
I don't know how it is called. I've customized but it based on the regular of W7.

This is classic theme:
http://3.bp.blogspot.com/-zqGiJCBubZI/Td51yumWL_I/...
This is modern/aero theme:
http://4.bp.blogspot.com/--VAFXW8L0IA/Td51yN6qm0I/...

See my reply here:
http://rammichael.com/7-taskbar-tweaker/comment-pa...

Oh.. The modern/aero theme. But of W7, not of Vista...

Both screenshots show Windows 7.
Anyway, there's an issue with the "show desktop" button on the classic theme.
It should work fine with the modern theme.

I don't know why it doesn't work properly for you. I've just checked, and it works fine for me on Windows 7.

Report:
I hoped it would fix also my modern/aero theme, but no,
The new advanced option: w7_show_desktop_classic_corner
didn't fix my problem.

The modern theme doesn't have a similar problem.
If it doesn't work for you, you must have another issue. Perhaps a conflicting program.

I could reproduce it on an RTL system.
Seems like a bug of Windows or explorer. The issues happens without the tweaker as well.