From that point of view, closing the browser is a significant event. Mozilla support sets the tone for Private Browsing here ( ): it protects against people who use your computer, but not malware and the such. Is the level of caution appropriate? Unchecked caution can become unhelpful. But forgoing that judgment, we may err on the side of caution, by preserving the user's clipboard data from such an unexpected loss. We may judge that as a bad decision by the user. In some cases, it might be the only copy. In the former case, when they do want it, we destroy a copy of some sensitive data. Always clearing it addresses the latter case, when they didn't want it. If a user really has left something sensitive on the clipboard, they either wanted it there or they didn't. Since the clipboard is a feature of the OS, and not of Firefox, they might also assume that it will still be there after Firefox closes. It's fair to assume that someone may copy some sensitive data to the clipboard. If we don't know whether the user wants their clipboard cleared or not, shouldn't we ask? PB sessions are a good place to access sensitive data. A compelling argument was sufficient at that point why not now? It'd be easier to accept the request for evidence, if the same bar had been applied to implement the feature in the first place. Life is easier without resorting to annoyance :) I hope users who are simply dissatisfied with the feature would suffice.

To attentive users, deleting contents of the clipboard feels like an intrusion. Personally, I don't know of any apps that touch it. a utility that converts all clipboard contents to plain text). A/V may scans many things, including the clipboard, for malicious activity or content), or specifically the clipboard (e.g. An exception might be when their purpose clearly involves some operating system function (e.g. Applications aren't to touch the clipboard for other reasons. A common assumption by users is that the OS provides the clipboard, and all applications do is get and put data upon the direct command of the user. Intrusive: A 'clear on exit' feature breaks the typical use contract between users and their operating system. It's possible that PB doesn't clear other areas, because they are left to the user/OS, e.g.: on the file system (slack space from temporary files or swap files), in RAM (previously-used stack or heap memory). Inside the perimeter, data can also flow from one tab to another, and one domain to another (see JavaScript's 'Single Origin Policy'). Data from a PB source could be exported before the browser closes, and before the PB session ends. Data could also be imported from outside a PB session by pasting data from outside sources. From this point of view, just clearing on exit only provides situational isolation. Looking at the possible dataflows, the clipboard is one. Incomplete: The overall goal seems to be isolation of data related to a Private Browsing session. With the clipboard is cleared only on exit, it feels incomplete and intrusive. Or, possibly, making only clearly-defined interactions with the OS clipboard. To achieve this, a custom clipboard should be implemented as a feature of Private Browsing, leaving the OS clipboard as a separate entity. It looks like the idea is a special 'Private' clipboard that breaks with the standard Operating System clipboard behavior, to improve data privacy control. The intention of this exaggeration is to make clear two simple reasons why the new clipboard-clearing behavior feels uncomfortable to a user. Please also consider making the clearing behavior optional, rather than default.Д«elow I explore an improvement, which I believe takes the motivation for clearing the clipboard to a further extreme. Please provide a way to disable this function of Private Browsing.

One comment issued recently on that bug, requests a way to disable the function via 'about:config'. This feature was implemented as with Bug 462106 ( ). Set to 'Private Browsing' indirectly, by selecting: Tools -> Options -> Privacy -> History -> 'Never remember history'Д¬opied text from within the content at the URL.ДЄttempted to paste the text into another application.

Firefox disable private browsing