[Skip forward to paragraph four to avoid the historical backdrop. ]
1. Seven or eight years ago I was working on a mini-app [1] in the browser
using VML. It allowed folks to build graphs on-screen with a GUI and then to do
standard graph theoretic things: color nodes, find shortest paths, find
dominating sets, copy and paste subgraphs, etc. I've been intermittently
rebuilding parts of it using SVG instead of VML [2], but it's been gnarly work
because of the ugly cross-browser development issues involving web apps. It
makes sense to me that WHATWG came into existence to address some of the gnarly
stuff like what I bumped into.
2. Over the years, I've watched with aggravated dismay, as well as curious
bemusement, as pieces of its once robust (albeit single-browser -- given its
use of VML) functionality have gradually been eroded by new releases of the IE
browser, as that browser moves, toward what I presume is standards compliance.
The app used to be able to read and write files to local drive space, to
commandeer CTRL key sequences used by the browser and the OS, (for example CTRL
T and CTRL D used to mean things in my app, but now the browser has taken those
over as its own) and all manner of other things that a user expects of an
application. If I were a company rather than a teacher/researcher, then I would
have spent the necessary hours to modernize the code, perhaps. But it was not a
product, but freeware and it was research that I was able to put on hold as my
interests mutated.
3. But some of the research has (because of what might be called imperial
entanglements) become relevant again, and so I find myself needing to provide
some fixes to some of the now derelict parts, or better, to move the stuff to a
more modern vector-based system like SVG.
4. Concerning the first thing I need to fix, I am not sure if HTML5 currently
provides a solution for. Here's the sitch: because of an extensive use of CTRL
sequences in the interface, the user will sometimes accidentally do something
like CTRL R (which the browser thinks is a refresh command). In a regular app,
if users stand in jeopardy of losing all their work, the app usually warns them
before quitting. The way I found to work around it (that used to work) was to
use onunload="confirm('save before quitting?'). Currently, however, IE seems to
have removed my ability to intervene before it erases all work.
onbeforeunload=function (){ fix(everything)} doesn't seem to help either.
So the question: how does HTML 5 currently address the issue and do browsers
actually implement something along this line these days?
Thanks for guidance here, and sorry if the issue has already been
satisfactorily resolved.
cheers
David
[1] http://srufaculty.sru.edu/david.dailey/grapher/ (IE only)
[2] http://srufaculty.sru.edu/david.dailey/svg/graphs18.svg (everthing but IE,
or IE/ASV)
