Hey instead of opening the new window you can have a new tab. This works exactly same as the new window works it opens a new tab in the same browser. When left clicked it should open new tab for this the setting has to me made go to menu(right most corner of the browser image attached)|preferences(setting symbol)|general there is option of tab check the option Open new windows in a new tab instead

What you explain is exactly the contrary of what I want, which I also mentioned in my OP. It's the same answer you see regularly on these questions, and isn't the same at all. Difference is, I will explain why it's not the same at all and a lot less handy working with tabs!

First of all, a new window shows up in the taskbar, a new tab doesn't. Then we have the issue with alt+tab. WIth tabs you have to use ctrl+tab, but it doesn't work as well as alt+tab. For example, when having 5 windows open, you can perfectly click on one window, then click afterwards on the other, from that moment on, pressing one time alt+tab, will switch to the other window, pressing it one more time again, will switch to the previous one. So even when you have 5 windows open, you can still choose between which two of those you want to switch with alt+tab. And you can change that by clicking on another window, from that moment, alt+tab will switch between that one, and the other one you just had openen before, those 2, don't need to be next together at all!

This is impossible with tabs, the only thing you can do with tabs is either ctrl+tab, then you will advance in the tabs in a serial way, and ctrl+shift+tab (ultra annoying) to reverse in a serial way between all tabs. Meaning you can't effectively switch between only 2 tabs alone, when more then 2 are open. Even when only 2 are open, it is annoying as hell.

Then we come to the next problem, with a new window, you can blindly close it by simply moving the mouse to the top right and clicking X. This is so easy that you don't even have to look at it while doing it, you just make the movement. Try that (without a shortcut) with tabs, no way you will even do that as the location of the "X" is always different depending on how many tabs are open.

So no, tabs are a very annoying and inefficient way of working compared to windows, when a user is handy with alt+tabbing. Totally not the same.

Again, what I need is, a one click on any link, and it needs to open always a new window! Tabs will never do!

"E.g.: I search something on google, get all results, and any result I will left click on one time, I will want it to open in a new window, that is the behavior I want as default (and not only on google)."

For Google searches see this: https://www.google.com/preferences

Where results open Open each selected result in a new browser window.

As far as a setting globally within Firefox, good luck with finding something to change it for hyperlinks.

I confirm the above: Firefox will normally open a link in the same tab unless it is specially coded by the site to open in a new window. Firefox's built-in settings can select between whether that specially coded link opens in a new tab instead of a new window, but I don't think there is a built-in setting to force regular links into a new window. You would need an add-on for that, or some sites like search engine results pages have an option for that.