Hi folks, for some weeks now, I'm getting my head around an interesting problem: I'd like to display a text file of several gigs, and let it be editable. Now - how would you do that? All standard approaches fail, because they rely on the file being fully loaded into RAM, which is impossible with several gigabytes of data. So, I thought I'll create a CustomControl. Basically, I've derived a Control from the Control class, which embeds a FrameworkElement in it's Generic.xaml. This FrameworkElement has a VisualCollection. Now, I hand over a Stream to this control. The Stream must be seekable and writable, otherwise you will encounter an exception. So far, I do the following: I read a chunk of data from the Stream, draw that using FormattedText on a DrawingContext, retrieved by a DrawingVisual. For scrolling, I simply adjust the offset of the FormattedText-function. To achieve seamless scrolling (which is needed, so you can scroll from one buffer chunk to the next without a visible gap), I have a function which calculates the amount of text that fits precisely into a rectangle (e.g. the Window's viewport), so that the rest of the current buffer, together with the next buffer, can be printed on the next rectangle. But, for the sake of it, I can't find out how I would do standard editing functionality. Because, for the scrollbar and this "chunking" to work, one needs to precompute the needed amount of text to fill the rectangle, which changes when editing the text. tl;dr: Do you have a smart concept on hand, together with WPF and C#, to create a TextEditor, which is capable of editing gigabytes of text?