Qt Creator right display margin incorrect - only works with certain zoom levels

Description:
When the zoom level is set to 106% (on a 1440p 16:9 screen) in Qt Creator, the right display margin in the text editor is misaligned by 2 characters. Although the right margin is configured to be at column 80 in Edit -> Preferences -> Text Editor -> Display, and "Tint whole margin area" is enabled, the tinted margin begins at character 78 instead of 80. This issue occurs with most zoom levels between 84% and 127%, but not at exactly 84% or 127%, where the margin is correctly displayed.

Steps to Reproduce:

1. Open Qt Creator 16.0.0 or 17.0.0-beta1.

1. Go to Edit -> Preferences -> Text Editor -> Display.

1. Set the right margin to column 80 and enable "Tint whole margin area".

1. Set the zoom level to 106% (or try other values between 84% and 127%).

1. Observe the position of the tinted right margin in the text editor.

Expected Result:
The tinted margin should begin at character 80, as configured.

Actual Result:
The tinted margin begins at character 78 when zoom is 106%, and behaves inconsistently for zoom levels between 84% and 127%.

Workaround:
Set the zoom level to exactly 84% or 127%, where the margin is correctly displayed.

I have attached screenshot for this issue.