DDLab Linux readme: Feb 2021 update
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There is just one execttable ...
ddlabz08_linux.tar.gz 64bit compiled in Ubuntu 16.4 LTS
(the 32bit version is discontinued, but available in ddlabz07 and prior)  

the .tar.gz file will unpack to give
ddlabz08_linux64, and GNU_GPL_3.txt.

To run DDLab:
from the directory with the DDLab file, 
enter the name of the executable preceded by ./ and followed by &
for example
./ddlabz08_linux64 &

Alternatively, first change directory to "ddfiles"
then enter the name of the executable preceded by ../ and followed by &
This will keep files generated by DDLab in the ddfiles subdirectory.

You can recompile DDLab for Linux yourself from the source code using 
Makefile_Linux_z08, available at
http://www.ddlab.org/download/ddlab_code_2021/ and mirror sites.
DDLab would appreciate news of alternative compiles.

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possible font issues in Linux Ubuntu (version 9.04 and later ?):
If the font files specified below can't be found,
ddlab will load alternative, unpredictable but acceptable fonts 
-- warnings will appear in the terminal)
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Recent versions of Ubuntu may no longer have 
xorg.conf (see below for the xorg.conf setup).
The fonts required by DDLab may or may not be available on your system.
In case not, the fonts are in directories: 100dpi, 75dpi, misc, 
in the file fonts_dd_linux.tar.gz, 
which can be downloaded from www.ddlab.org/download/
As root, place these directories in /usr/share/fonts/X11/

to restore DDLab contents when uncovered by another window
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(not an issue in ubuntu 16.04 LTS pre-installed in Dell XPS13)

In Kubuntu 11.04 (KDE), "Desktop effects" must be active.
In Ubuntu 11.10 (Gnome) you might need to do the following:
as root, create a file /usr/share/X11/xorg.conf.d/05-backingstore.conf
and putting this into it:

Section "Device"
        Identifier "Default device"
        Option "Backingstore"
EndSection 

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  font issues for older linux versions:
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You might need to modify (as root) the X11 config file,
which has a different name for different versions of Linux:  
SuSe (and RedHat?): /etc/X11/XF86Config
Ubuntu (Kubuntu):   /etc/X11/xorg.conf

1. FontPath:
   in section "Files"
   you will see various FontPath(s) listed ---
   if any are missing, they should be added.

   for SuSe (and RedHat?), add the following (if missing)
   FontPath      "/usr/X11R6/lib/X11/fonts/misc"
   FontPath      "/usr/X11R6/lib/X11/fonts/75dpi"
   FontPath      "/usr/X11R6/lib/X11/fonts/100dpi"
   
   for Ubuntu (Kubuntu), add the following (if missing)
   FontPath      "/usr/share/X11/fonts/misc"
   FontPath      "/usr/share/X11/fonts/75dpi"
   FontPath      "/usr/share/X11/fonts/100dpi"

   also, for ddlab to work on the GNOME desktop, add (if missing) 
   FontPath      "unix/:7100"


2. BackingStore - to keep the contents of DDLab when changing/hiding 
   windows, the following should be in the config file,
   in Section "Device" (not Section "InputDevice")
   you will see various things listed,
   add: Option "BackingStore"
   i.e.
   Section "Device"
        Identifier   "Neomagic Corporation|NM2360 [MagicMedia "
        Driver       "neomagic"
        BoardName    "Unknown"
        Option       "BackingStore"
   EndSection

   However, if you switch workspaces (desktops) in KDE or GNOME
   the previous images in the DDLab window might be lost.
   In FVWM this problem does not occur.

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