Hi,
Also better handling of tabs is added in https://www.ventismedia.com/mantis/view.php?id=17575

I think showing tab content is preferred over showing the close button, especially as right click allows you to close the tab.

I don't know if it is "normal", but I can replicate your issue if I create more than 12 tabs.
The tabs get so small, that they squeeze out the x boxes.
But I would hesitate to call it a bug, because the Chrome Browser does exactly the same thing.
But then the Chrome key is more elegant in this situation, because it has a mouse hover tool tip for each tiny tab to describe the tab's contents, and they also have control key shortcut keys to navigate to either end of the long list of squashed up tags. (ctrl+1 and ctrl+9)

Did you create that many tabs on purpose? They help you somehow?
I think that the issue is that the MM Devs were clearly not expecting a user to create that many tabs.

Thanks Barry4679.

Is it normal that some ones are with x buttons some without?

If you right click a tab, other the rightmost, there is a option for "Close Tabs to the right"

As you can see some of the shown tabs are without x buttons, so it is not possible to close them at all. User has to close ones with the x button first to make some free space for other tabs.