Thanks for screen shots, I am happy to get feed back from Linux users as I don't have direct access (yet?). I think Chris the developer of SmallBASIC has moved from FLTK as it has been discontinued. I am not clear on tech details but I can pass questions on to Chris. I do know the Windows FLTK editor and samples have been removed from Download board and his goal is to get all platforms working from one version of SmallBASIC currently at 0.12.2 (or as close to one version as possible).
A couple more notes:
You will find 2 constants xmax and ymax that give you your screen dimensions (in pixels) you have to work within. Unlike other Basics you don't set the screen size or mode, its all from the same screen, so a newbie is saved from those details getting started with SmallBASIC. Check with this
print "My screen width is ";xmax
? "My screen height is "; ymax '<= comment is common symbol and at least on other BASIC uses ? as PRINT shortcut
There is a built in editor or you can use plain text files with .bas (and I think .txt) extensions, say from Windows Notepad.
From command line, use -e or -r switches for edit or run.
In Windows, at least, you can drag drop files onto SmallBASIC application icon and of course register .bas in Windows to SmallBASIC and just click the .bas file (not recommended unless SmallBASIC is your main BASIC)
The built in editor is rather quirky (and new). The general rule is whenever it seems hung, like after a help or run and syntax error found, PRESS esc to get 'focus' back into main part of editor.
+ Errors from runs are posted in top right corner of screen and until you press esc, you can't start editing the error.
+ Language reference help including keyboard shortcuts are accessed ctrl+h, until you press esc the 'focus' is in help, the right side of the screen.