trisquel-gtk-theme: Window Menu button mouse-over area doesn't extend to top-left pixel when maximized (fitts' law)

Suspected upstream issue: https://gitlab.gnome.org/GNOME/gtk/-/issues/6034

When a window is maximized, the mouse-over area for the Window Menu button does not reach the top-left pixel, which violates Fitts' law. This causes two main problems:

• The appearance of themes seems broken, leading developers to attempt fixes without realizing the issue originates upstream.
• People who configure the close button to be located at the top left—including left-handed users and those who are accustomed to this layout, such as macOS users who migrate to other systems—often do so for comfort or familiarity. However, they cannot close windows as easily or quickly as right-handed users who use the default top-right position, as shown in the screenshots below.

Theme notes

This is not an issue with the theme's button itself.

However, when evaluating this bug, ensure you use a theme that is not affected by the well-known top-right pixel issue. For example:

• Only the 'BlueMenta', and 'Menta' mate-themes package are not affected by Virtually all MetacityThemes' close button's mouse-over area don't extend to top-right pixel when maximized (fitts' law)
• The Trisquel-specific themes included in the trisquel-gtk-theme package (as shipped with Trisquel GNU/Linux) are also unaffected.

Also, Firefox and Thunderbird should not be evaluated since they are using a custom Metacity theme that are not affected by this issue. Use other programs such as the file manager that ships with your distro.

Steps to reproduce

• Maximize the window
• Move the cursor to the top right corner; it will display "Close Window" and close the window when you click.
• Place the mouse cursor in the top right corner. The "Window Menu" label does not show up.
• Click on left mouse button. The Window Button is not accessed.

Example with the 'BlueMenta' theme from the mate-themes package:

Referencing #214 (comment 13662) :

It looks like there is a left margin for the window top border, but no right margin.

I am getting the same behavior as described, but reversed, if I reverse the position of the buttons on the border, selecting Left (with menu) instead of Right (with menu) in MATE Tweaks > Windows > Appearance.

Expected result:

Images manipulated screenshot to demonstrate the expected result:

MATE Tweaks > Windows > Appearance configured Left (with menu) instead of Right (with menu)

Other Fitts' law issues

• GtkHeaderBar: Close button's mouse-over area doesn't extend to top-right pixel when maximized (fitts' law)
  • Note: Solved with https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/8386 but does not solve the issue for the Window Menu button.
• Manual window enlarging limitation (fitts' law)