Never denied it was LCL, but where in LCL?
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In both themes (or all themes you tested),
with the current/unfixed LCL,
if you compare the IDE menu, against Notepad:
Both have "File Edit" as the first 2 items.
Is the distance, between the leftmost pixel of "File" (the vertical line in F) and the leftmost pixel of "Edit" the same?
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What are the "Margin" values in GetVistaBarMenuMetrics
debugln at the same place, but get the value of the magins.
And a bit further down: In "procedure DrawVistaMenuBar"
there is a param "ARect", what are the values of that?
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If you are on it, currently it gets TMT_CONTENTMARGINS
Also get TMT_CAPTIONMARGINS and see what they are.
We are not the only ones:
http://social.technet.microsoft.com/Forums/windows/en-US/e986ff2d-64b6-4c5f-b13f-5ac8fbfb00d3/delta-to-menu-bar-item-width-returned-in-wmmeasureitem?forum=itprovistadesktopui