When a focused tab has a bold tab-title, then other tabs are a little bit moving while tab-browsing

[ralf3u]

Steps to reproduce the issue
make the tab-title of a focused tab bold (see below in "Remark I" how this works)
open many tabs
tab-browse to the left or to the right

Result
Other tabs that are not in focus are moving a little bit to the side

Expectation
Other tabs should not move at all

Remark I
If geany.css does not exist in .config/geany, type this code in the terminal:
cp /usr/share/geany/geany.css .config/geany/
Open geany.css that is located in .config/geany/
Add at the end of the document those lines:

notebook tab:checked label {
	font-weight:bold;
}

Save the document, close Geany, open Geany

Remark II
I use an ePaper-display in that way that only the black color is on the screen.
So, after an installation of Geany, when many tabs are open, I can't see at all which tab is in focus and which tab was changed, but not saved.
I add in geany.css in geany-document-status-changed the following code to see which tab was changed but not saved:
font-style:oblique;
And I delete there the color.
And this is what I use in geany.css for the tab that is in focus:

notebook tab:checked label {
	color:white;
	background:black;
}

I would prefer to use bold, but then some tabs are a little bit moving while tab-browsing.

Geany 1.38

[elextr]

First of all, if your theme font for application tabs is not monospaced there is no guarantee that bold is the same width as non-bold.

But even if your font is monospaced it is known that some fonts use "fake bold" to generate a bold version from the non-bold version, but the width of the characters is changed by the process.

So its not entirely surprising that things move when the state changes.

[ralf3u]

... if your theme font for application tabs is not monospaced ...

In Lubuntu with the desktop environment LXQt Desktop, I found in main menu, Preferences, LXQt Settings, Appearance the value Font. If I mark the value Font, then I see as Default font for user interface the font name Ubuntu.

Do you mean this?
Which font name should I take?

[ralf3u]

In main menu, Preferences, LXQt Settings, Appearance, the value Font, I tried some fonts. With those fonts the issue does not appear any more: aakar, Abyssinica SIL, Jamrul, Liberation Mono, Khmer OS System, Kinnari and Likhan. I chosed Liberation Mono, with the Style Normal and Point size 28. That's so cool!

Thank you so much for your help.