Wednesday, October 31, 2012

Wide Margin 1.1 Released

I am please to announce the release of Wide Margin 1.1

Wide Margin 1.1 comes with a load of usability improvements and bug fixes.

New Features include:
  •  Mouse driven passage lookup
  •  Filtered Searches
  •  Continuous Scrolling for search results
  •  Target verse highlighting

I want to say a big thank you to all the people who contributed to this release to make it possible.

The application can be downloaded here and supports both ubuntu and windows.

Wide Margin is free and opensource and is produced entirely by volunteers. If you would like to help or contribute please visit our website:

Monday, October 8, 2012

Invoking on the UI thread in GTK#

Not Threadsafe
GTK like most GUI toolkits is not thread safe. This means that you must only ever update it form the UI thread. If we want our applications to be responsive however we must run any long running processing on a different thread so that the UI thread is free to respond to user input. This posses a problem because we need to be able to update the UI to reflect the progress and outcome of the processing, but we can't do that directly because the UI is not threadsafe.

How to update from another thread without updating from another thread
Fortunitely GTK# has a built in mechanizm for running code on the UI thread from another thread. This mechanism is call Application.Invoke and you can call it like this.

Application.Invoke((_,__) =>
    // update UI here

This method however is suboptimal, firstly because Application.Invoke takes two parameters (object sender, EventArg args). In most cases we don't need these and so in my example I have used _ for the sender and __ for the args. The second problem is that we only really need to call this if we are not already on the UI thread. We don't want to take on the penalty of the overhead if we are already on the UI thread.

There must be a better way
In winforms useful methods are provided which solve the problems presented by Application.Invoke.

The first is Control.InvokeRequired this will return true if we are not on the UI thread or false if we are.

The second is Control.Invoke this is like Application.Invoke but without the overhead of having to specify a sender and args and can be called like this:

Control.Invoke(()  =>
    //update UI here

By combining these you can write code that only invokes when it needs to. The details of this can be found here:

Can we do that in GTK?
Yes we can. We can achive exactly that using Extension Methods. Actually we can improve on it by making the Invoke method only call Application.Invoke if we are not already on the UI thread. The following code is provided under the Unicorn licence.

Doing this means that what was:

Application.Invoke((_,__) =>
    // update UI here


Invoke(()  =>
    //update UI here

Which is cleaner and takes care of figuring out what thread your are on for you.

Saturday, September 15, 2012

Wide Margin 1.1 hits Beta

I am please to announce that the 1.1 release of Wide Margin has hit Beta.

Changes since 1.0 include:

  • Mouse friendly passage navigation and filtering.
  • Search Filtering.
  • Continuous scrolling on search results.
  • Windows support.

How ca you get it?
The windows version can be downloaded from here:
The ubuntu version can be installed from our PPA:

How can you help?
At this stage we need testers. We need people to install and use Wide Margin. If you find any problem please raise them on our bug tracker here: