sudo gedit /usr/share/applications/opera.desktop

Find the line I mention above (the 7th one) and change it to what I say. Then save and exit.

Exec=opera %U

to

Exec=opera %U --start-maximized

And here are the contents of the whole opera.desktop file if you want to check

http://paste.debian.net/937473/

(the link is valid for 7 days)

Opera now doesn't open properly in Linux Mint anymore, it doesn't open maximized by itself.

If you open the launchers and change the command from "opera %U" to "opera %U --start-maximized", then it opens mid-size at first, then jumps to maximize. This is great!

However, this only works in each specific launcher, and the "new window" and "new private window" options from the icon on the taskbar/panel, well, their launchers are "missing" - can't find them anywhere.

Below is the file "opera.desktop" from "/usr/share/applications" in Linux Mint 18.1 Cinnamon.

it's the only file I can find that refers to "new window" and "private window" - I couldn't find anything about opera in "~/.local/share/applications/" but there's other copies of this in

/home/Username/.local/share/applications/userapp-opera-KE9M0Y.desktop
/home/Username/.cinnamon/panel-launchers/cinnamon-custom-launcher-1.desktop

But when I edit the 2 lines that say

"Exec=opera --new-window" to say "Exec=opera --new-window, --start-maximized"
and
"Exec=opera --private" to say "Exec=opera --private, --start-maximized"

there's no change in the window behaviour. What am I doing wrong here?

This is the file, I edited it as root even:

[code][Desktop Entry]
Version=1.0
Name=Opera
GenericName=Web browser
Comment=Fast and secure web browser
TryExec=opera
Exec=opera %U --start -maximized
Terminal=false
Icon=opera
Type=Application
Categories=Network;WebBrowser;
MimeType=text/html;text/xml;application/xhtml_xml;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/ftp;application/x-opera-download;
Actions=NewWindow;NewPrivateWindow;

[Desktop Action NewWindow]
Name=New Window
Exec=opera --new-window
TargetEnvironment=Unity

[Desktop Action NewPrivateWindow]
Name=New Private Window
Exec=opera --private
TargetEnvironment=Unity[/code]

I'm really getting lost here - do we have someone who can see what I'm doing wrong? Does anybody know the right syntax for this? Specifically the "EXEC" lines.

and it shows "-start-maximized" as a parameter.

Put it in the Opera launcher and bingo.
Opera now opens maximized with this command in the launcher:

in Linux:

opera %U --start-maximized