Hello! Is it possible to start Opera Developer directly into a private Window? Is there any command line switch for this?

2 Problems with Opera developer 37.0.2171.0 on windows 10 32bit

1. Print preview doesn't work, printer dialog is looping endless on preview.
2. Web.whatsapp.com only shows error message : ...works only with google chrome 36+

At least the printer problem didn't show up in previous version 2163.

Hi treego, both videos are playing without any problems with Opera 31 beta (31.0.1889.92) on my Windows 8.1 32bit system.
Maybe its a problem with Windows 7?

Found out its caused by extension "user agent switcher". Was set to "Opera on Windows". If i set it to "Opera Dev" Whatsapp Web is working well.

Whatsapp Web app (https://web.whatsapp.com/) doesn't work any more with last beta. Get only the message: "WhatsApp Web funktioniert mit Google Chrome 36+, Um WhatsApp Web nutzen zu können, aktualisiere Chrome oder besuche Mozilla Firefox, Safari, oder Opera. AKTUALISIERE GOOGLE CHROME".
Suppose its caused by the chrome version used. In Google Chrome Browser Whatsapp works well.

Activated sidebar on opera beta. but cannot install new sidebar extensions because the sidebar extension category isn't displayed. This didn't occur with opera developer 29.

Hi, I solved my java problem: it was caused by the plugin settings: I had not checked " execute all plugins" but "execute important plugins"

After installing Opera developer 29.0.1794.0 (windows 8.1 32bit) i installed java 8.40 and now java doesn't work at all in the browser. When using the java test page https://www.java.com/en/download/installed.jsp I only get the error message that the page abended (i don't know the exact english text because the message is in german). Same when I try to test java applets. The java installation went well and i can test java successfully in other browsers like firefox.

Hi @l33t4opera: Thanks a lot for your useful tips. I solved the problem with the print preview already. It was my fault, i disabled the internal chrome pdf viewer plugin because I'm using the pdf extension, but the print preview needs the internal pdf viewer.

Question: Is there a way to start opera with all extensions disabled? Would be useful for problem determination.