Firefox as a default browser

[Stephen]

When I start Firefox in an IE I am always asked if I want it to be my default browser. if I go to Firefox settings I cannot make Firefox my default browser because the setting does not change when I click on it. When I start Firefox with ReHIPS disabled, then the pop up about making it my default browser does not come up.

What can I do to make Firefox my default browser when it's running in an IE?

When I run Firefox with ReHIPS disabled, then the Firefox Options pages have a dark background. However, when I run Firefox in an IE the same pages are shown in their default white background. Why is there this difference?

My suspicion is that these problems are related.

To give a more complete picture I should add that I checked the Copy User Data, started Firefox and then after closing Firefox I unchecked it. Anyway, even if I check it again, the problems that I described above continue to exist.
In Program Settings, Privileges I have checked Set Hooks and unchecked Use Separate Desktop.

[fixer]

I remember you're using Windows 10. From Windows 10 programs are not allowed to explicitly set themselves as default file handlers. So Firefox can't explicitly tell: now I handle http, use only me. Instead it shows a Settings->Default apps window and humbly waits for the user to set it as default. This requires interaction with shell and isolated Firefox can't do it. And to be honest, you don't need it. Only file associations for your real user matter, they define which browser will be opened for http. So the best way in this case is to simply disable this check for isolated firefox.

Background color is probably related to Set Hooks being disallowed (which is the case in firefox default rules). I have firefox 70.0.1 and I see white background in both isolated and non-isolated firefoxes. Does it pose any difficulty?

[Stephen]

I disabled checking if Firefox is my default browser. It seems to work, that is I'm not being asked if I want to set it as my default browser.

As regards the background color of the Options pages, I have the same version of Firefox as you, but in my case if I start Firefox with ReHIPS disabled, the Options etc. pages are dark. If I enable ReHIPS and start Firefox, then the Options etc. pages are white. I have unchecked Copy User Data.

I don't know if it's relevant, I installed an add-on to Firefox while ReHIPS was disabled. When I started Firefox with ReHIPS enabled, the add-on was missing. I installed it again.

It's as if there are two separate installations of Firefox (at least as far as the settings are concerned), one with ReHIPS disabled and another with ReHIPS enabled.

[fixer]

You're right, all settings are copied into isolated environment. And it looks like there are 2 separate Firefox instances: one non-isolated and one isolated, each with its own set of settings.

Why was it done this way? For security purposes. The real settings aren't synced with isolated environment so you could use non-isolated firefox for example for banking and isolated instance has no access to banking settings in case you could have saved something sensitive (though you can resync it by removing isolated environment and reinstalling default rules). And isolated settings aren't synced with real environment as they're treated as compromised and who knows what they contain.

[Stephen]

Thank you very much for the explanation. The better a user understands how some settings work the less risk there is that he or she will not make a mistake.

Based on your explanation, I would like to ask if I remove Firefox's IE and reinstall the default rules would only those rules for Firefox be reinstalled or would reinstalling the default rules (by clicking on the relevant button) also reinstall rules for any other programs that are not working an an IE, but for which I may have changed some settings?

[fixer]

When you install rules from the Programs tab, RulesManager comes into play. Here is a blogpost about rules installation https://forum.rehips.com/index.php?topic=9529.0

In short words, if some rule is already present in ReHIPS database, it won't be overwritten, only missing rules will be installed. So if you deleted Firefox rules, they'll be reinstalled. If you modified some other rules, they're present and won't be reinstalled. But if you deleted some other rules, they'll be installed back, that's why here https://forum.rehips.com/index.php?topic=11838.0 I recommend not to delete rules, but to change them instead.

[Stephen]

Thank you for the clarification.