SDK center image (logo) in the custom sections to the Plug-in Manager

I've always found layout of controls fussy. To center a picture or any other control, I generally use this idiom:

f:row {fill_horizontal = 1,
    f:spacer {fill_horizontal = 1},
    f:picture {...},
    f:spacer {fill_horizontal = 1}}

The row will expand to fill the width of its container, and the two spacers will then expand equally in that width. You can omit the row if the container has a width determined by its other contents.

To left-justify the control, omit the second spacer, and to right-justify it, omit the first spacer.