Use UTF-8 mode

[thelink2012]

IUP uses a encoding depending on the C locale, Rust is Unicode aware by the means of UTF-8. Thus the UTF-8 mode of IUP must be enabled by us right after calling IupOpen, the global attributes are UTF8MODE and UTF8MODE_FILE (docs here).

Additionally it should be clearly documented we turn UTF-8 mode ON so the user don't need to worry about it.

[dcampbell24]

It looks like this is only supported in GTK and Windows. I think we could use the target_os cfg attribute to test whether the platform is a GTK or Windows platform (see Product -> Availability). Maybe there is also some way to get this information from IUP directly that I am unaware of. If the platform is not GTK or Windows, we should at least print a warning during IUP initialization.

[thelink2012]

There's a DRIVER attribute that specifies the current backend (GTK, Motif or Win32). Though I don't see it as a major issue as Motif is supported by IUP only because Tecgraf legacy applications need it on the older platforms they run, i.e. it'll mostly like be always GTK or Win32.

[thelink2012]

The Drag&Drop system says the following:

Here are some common Drag&Drop types defined by existing applications:

• "TEXT" used for regular text without formatting. Automatically translated to CF_TEXT in Windows.
• content MIME types, like "text/uri-list", "text/html", "image/png", "image/jpeg", "image/bmp" and "image/gif".
• "UTF8_STRING" in GTK and "UNICODETEXT" in Windows.
• "COMPOUND_TEXT" in GTK and "Rich Text Format" in Windows.
• "BITMAP" and "DIB" in Windows. Automatically translated to CF_BITMAP and CF_DIB.

Not sure if we need to handle this, but needs to be checked.

[thelink2012]

UTF8MODE and UTF8MODE_FILE are now active (and gives a println warning on Motif), however this issue should not be closed yet.

• This must be documented somewhere.
• This Drag&Drop case posted above needs to be checked.

[thelink2012]

UTF-8 mode is now documented on 6e2a2bc62. Drag&Drop still needs to be checked.