Terminal screen display handling

Compared to I4GL, Genero BDL uses an optimized and specific design to handle terminal display, that introduces some differences.

TERMCAP/TERMINFO

Genero BDL uses termcap/terminfo based solutions and therefore supports all kind of terminals the IBM® Informix® 4GL supports.

For more details, see Using a text terminal.

Remaining DISPLAY AT text

With IBM Informix 4GL, displaying text to the current window is a direct rendering method, and no trace of the displayed text is keep. When chaining interactive instructions and various forms with code using DISPLAY AT instructions, it is possible that some phantom text remains with I4GL when a previous window/form is re-activated.

Genero BDL implements the user interface with the concept of Abstract User Interface, a XML tree that keeps the elements that have been displayed by the program. Consequently, a text shown with a DISPLAY AT instruction will remain, even after closing a window/form that was hiding this text. With I4GL, the text disappears.

Regarding DISPLAY AT, the behavior of Genero BDL is more consistent than I4GL.

TTY attributes not reused in new INPUT

With IBM Informix 4GL, an INPUT dialog without ATTRIBUTES clause defining TTY attributes, reuses the TTY attributes that were set by a previous dialog. For example, when an OPEN WINDOW defines TTY attributes, then an INPUT dialog without TTY attributes is executed, followed by another INPUT with TTY attributes, then again by the INPUT without TTY attributes: The last INPUT uses the TTY attributes defined the second INPUT:

OPEN WINDOW w1 AT 2,2 WITH FORM "form1"
     ATTRIBUTES(BORDER,BLUE,UNDERLINE)
...
INPUT BY NAME rec.* WITHOUT DEFAULTS
...
INPUT BY NAME rec.* WITHOUT DEFAULTS ATTRIBUTES(RED,REVERSE)
...
INPUT BY NAME rec.* WITHOUT DEFAULTS -- gets RED,REVERSE
...

With Genero BDL, any new INPUT without TTY attributes always uses the attributes defined by the OPEN WINDOW. This behavior is more consistent than I4GL.

If needed, review the program logic and explicitely use the TTY attribute you want directly in the INPUT dialog.