Unable to change margins in mPDF theme options

[josieg]

Description

When I try to change the margins in mPDF theme options, my changes are removed after I click "Save."

Expected behaviour

I expect that when I change the margins in mPDF theme options, that my changes will be preserved and applied to the next mPDF export when I click save.

Actual behaviour

I open mPDF theme options. I change the left and right margins. I click save. The values in the left and right margins are reverted to their original values.

Steps to reproduce the problem

1. Open mPDF theme options for a book.
2. Change left margin to 20.
3. Change right margin to 20.
4. Click save.
5. Watch the margins change back to 15 and 30.

[bdolor]

resolved via 5992a7e

[josieg]

I can now change the margins (and by that I mean I can edit the margin numbers in mPDF theme options and have the numbers I enter stay there when I click save.

However, the margins in the mPDF are unaffected by these values. The mPDF consistently exports what looks like 10mm margins on each side, even when I have it set as 30 and 40 mm on right/left sides.