Monday, January 4, 2010

GeckoFX Multi v.1

Download GeckoFX Multi v.1

What is it?

GeckoFx Multi is modified GeckoFx library which:
  • Has built-in discovery of Gecko's based applications (like Firefox)
  • Can be used with any Gecko version from: 1.8.1, 1.9.0, 1.9.1, 1.9.2b5, meaning it is compatible with the installations of:
XULRunner 2.0.x-... (Gecko 1.8.1.x-1.9.2b5)
Firefox 3.0 (or any other Gecko 1.9.0.x installation)
Firefox 3.5 (or any other Gecko 1.9.1.x installation)
Firefox 3.6b5 (or any other Gecko 1.9.2b5 installation)
  • Single library (single compilation) for any Gecko version.
GeckoFx Multi will probably retain compatibility with Gecko 1.9.2 (release of Firefox 3.6), but this can't be guaranteed at the moment.

Getting Started

GeckoFx is a very nice library developed by Skybound Software, which has one little drawback: it can be used only with specific version of XULRunner it was compiled for. It's not a big deal if
you are able to redistribute the always up-to-date XulRunner with your software, but it becomes a problem if your installation has to be as small as possible and you want to use Gecko installed at user's system (for example Firefox browser, which will probably be up-to-date itself).

Example of such program is HLR Ban Poster (, with setup less than 1 mb in size, which autodetects and uses any Gecko available at user's system, and can rollback to standard Microsoft WebBrowser control in the worst case.

GeckoFx Multi uses proxies and custom marshalers to retain compatibility with xpcom NS interfaces changed in different Gecko versions.

Reliability and Compatibility

GeckoFx Multi modification was developed especially for use in one particular project (HLR Ban Poster), and wasn't throughly examinated in other conditions. All code inside original GeckoFx for supporting different Gecko versions was retained and converted, but wasn't throughly tested, so 100% compatibility can't be guaranteed.

In some situations GeckoFx Multi may work worse than original library, so if you need a stable Gecko-based control working with single dedicated version of Gecko engine I recommend using the latest library from SkyBound website ( instead.

How to use

The same way like you used usual GeckoFx. The same control, the same initialization, GeckoFxMulti should work instead of original GeckoFx library without any code modifications.

If you want to initialize GeckoFx with the latest supported version of Gecko present in the system (searches registry for applications distributed with Gecko (like Firefox), release versions are preferred over alpha/beta) use the following initializer:


The other possibility is to get all geckos detected at the system and give user the ability to select the desired one:

// just use auto detection
var gad = Skybound.Gecko.GeckoAppDiscovery();
// use auto detection and provide several custom gecko paths to check.
// you can also add custom gecko path to check using AddGeckoPath method

var gad = Skybound.Gecko.GeckoAppDiscovery("c:\\xul2.0", "c:\\firefoxportable3.6b5");

After Gecko's discovery you can retrieve the list of all or valid-only geckos using the gad.Geckos or gad.ValidGeckos properties. Also you can initialize a single GeckoAppInfo class this way:

var gai = new Skybound.Gecko.GeckoAppInfo("d:\\firefox");

When your GeckoAppInfo structure is prepared (selected from ValidGeckos list or filled in manually), you can pass it to the Initialize method:


Please note: you can't initialize several Gecko's at once or one after another, the only possible solution to let user pick second Gecko and initialize it is to restart your process (if your software is using a separate AppDomain for Gecko browser, it should be possible to reload just this AppDomain).

Changelog v.1 based on GeckoFx (4 Jan 2010)
  1. Merged SkyBound modifications for GeckoFx
  2. nsIDOMHTMLDocument.Get/SetTitle: changed back to nsAString, nsAUTF8String (introduced at GeckoFx 1.9.1) seems inappropriate here.
  3. Support for PreAlpha/Alpha/Beta Gecko sub-versions.
  4. Prepared for public release (additional constructor, etc).
  5. Preliminary support for Gecko 1.9.2 (tested with Firefox 3.6b5).


  1. Hi!

    Do you know how to obtain an editing session for nsIHTMLEditor with GeckoFX?

  2. Dear brainsucker,

    I am really impressed by your creativity in making gecko fx available for all platforms. Kodus to you.

    I have successfully integrated your DLL into my browser however, I want to add interfaces that have different iids for each xul version. So I put in the interface in the following format

    [xpcVersion(0x1090100, 0x1090200)]
    interface interface_name

    [Guid(iid for mozilla 1.9.1), ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]interface interface_name_01090100

    [Guid(iid for mozilla 1.9.2), ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnkinterface interface_name_01090200

    And it works for some interfaces, while others end up giving me this error when called:

    + Exception {"Unable to cast COM object of type 'System.__ComObject' to interface type 'Skybound.Gecko.[interface name]'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{7E1C0A09-DDD2-37A1-986B-B48963656545}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE))."} System.Exception {System.InvalidCastException}

    So I was hoping you could lend a hand and if possible, make the process to add future interfaces easy in the next version.

    Please email me at when possible.

    Thanks in advance.


  3. Latest nightly? :) Gecko 1.9.2.x shouldn't contain any groundbreaking changes...
    If you are talking about gecko 2.0, then it is not supported yet (it MIGHT be supported in the future if Skybound will port original GeckoFx for gecko 2.0 (firefox 4), cause I'll probably never find enough time to do it myself).

  4. Hey brainsucker i really need your help I am using your Gecko Multi control in one of my WPF Application and i need to submit Form automatically I know it is possible using MozNet but i dont want to invest money as i am a start up developer.Please can u help me on how to submit the Form loaded in the GeckoBrowser.