Screen resolution by default is 1024 x 768 after installing Zorin OS. Following below command lines to set it to be the native resolution of a Dell IN1920, 1360 x 768.
$ xrandr
Screen 0: minimum 8 x 8, current 1024 x 768, maximum 32767 x 32767
DVI1 unknown connection (normal left inverted right x axis y axis)
1360x768 59.80
1152x864 60.00
1024x768 60.00
800x600 60.32
640x480 59.94
VGA1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1024x768 60.00*
800x600 60.32 56.25
848x480 60.00
640x480 59.94
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
$ gtf 1360 768 60
# 1360x768 @ 60.00 Hz (GTF) hsync: 47.70 kHz; pclk: 84.72 MHz
Modeline "1360x768_60.00" 84.72 1360 1424 1568 1776 768 769 772 795 -HSync +Vsync
$ xrandr --newmode "1360x768_60.00" 84.72 1360 1424 1568 1776 768 769 772 795 -HSync +Vsync
$ xrandr --addmode VGA1 "1360x768_60.00"
$ xrandr
Screen 0: minimum 8 x 8, current 1024 x 768, maximum 32767 x 32767
DVI1 unknown connection (normal left inverted right x axis y axis)
1360x768 59.80
1152x864 60.00
1024x768 60.00
800x600 60.32
640x480 59.94
VGA1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1024x768 60.00*
800x600 60.32 56.25
848x480 60.00
640x480 59.94
1360x768_60.00 60.00
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
$ xrandr -display :0.0 --output VGA1 --mode 1360x768_60.00
$ xrandr
Screen 0: minimum 8 x 8, current 1360 x 768, maximum 32767 x 32767
DVI1 unknown connection (normal left inverted right x axis y axis)
1360x768 59.80
1152x864 60.00
1024x768 60.00
800x600 60.32
640x480 59.94
VGA1 connected 1360x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1360x768 60.00 +
1024x768 60.00
800x600 60.32 56.25
848x480 60.00
640x480 59.94
1360x768_60.00 60.00*
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
