1.7.4 no back compatibility

[Kilinich]

Some scenes created in 1.7.4 cannot be opened in 1.7.1
for example:
http://www.algodoo.com/algobox/details.php?id=43536

[Chronos]

Obviously. Why would you want to use an old version of a program?

[tatt61880]

Obviously. Why would you want to use an old version of a program?

Please imagine that when you upload scene into Algobox, you may get comment "this scene don't load in algodoo :s".

I suggest adding feature to show error-message (e.g. "Error: This scene was made by Algodoo v1.7.4").

[Mystery]

1.7.4
Shadow under text is not good for compatibility. Some old scenes looks ridiculous.
Default font/size/text-fit-in-box is changed so spawned box with text in old scenes shows incorrect way - not like it was designed.

I think better is left everything as it was by default for scripts and old scenes, but if you create box from gui - set new cool font, filling, etc.

The new text system, based on Pango, is superior to the old in many ways - it supports Unicode, markup and many different fonts and styles. But it also has drawbacks - it's slower than the old system and it doesn't produce the same output on all platforms. Now, I could keep both systems and use the old one where appropriate - but that would mean twice the code to maintain, which will make future fixes and changes in the code base a lot more work. So I decided that the upsides of the new system out-trumped its downsides, and decided to keep the new system and scrap the old one.

This is a general problem with changing engines mid-flight - it will never go over perfectly without a hiccup. The alternative is a system where we release once, and then never updates (except for bug fixes). And then, after a few years, we release "Algodoo 2" - which makes no guarantees about back- or forwards compatibility with "the old" Algodoo. Now, we could do it like that - but then again, you could all just pretend that's what we're doing, by ignoring all upgrades for a few years at the time.

The bottom line is: the only reasonable way to ensure compatibility is to have only one, never-changing version. And I think that would be sort of boring.