Installation of Virtualbox 6 on Linux Mint 19 (based on Ubuntu Betsy):

sudo apt-get purge virtualbox-qt virtualbox-ext-pack virtualbox-dkms
sudo apt-get remove virtualbox

wget -q https://www.virtualbox.org/download/oracle_vbox_2016.asc -O- | sudo apt-key add -
echo "deb [arch=amd64] http://download.virtualbox.org/virtualbox/debian bionic contrib" | sudo tee /etc/apt/sources.list.d/virtualbox.list
sudo apt-get update
sudo apt-get install virtualbox-6.0
sudo vboxconfig

For Debian 9 / LMDE 3 replace bionic with stretch in the apt line above.

Various Notes:

Seamlessrdp from Linux to Win7:

https://acmyau.wordpress.com/2011/12/07/seamlessrdp-from-linux-to-windows-7/amp/

https://github.com/rdesktop/seamlessrdp

Seamless windows: integrated taskbar:

https://forums.virtualbox.org/viewtopic.php?f=9&t=2500

https://www.mail-archive.com/search?l=vbox-dev@virtualbox.org&q=subject:%22Re%3A+%5Bvbox-dev%5D+seamless+taskbar+integration%22&o=newest&f=1

Prevent maximised window from using area of screen:

https://unix.stackexchange.com/questions/355291/prevent-maximised-window-from-using-top-few-lines-of-the-screen-in-kde

https://superuser.com/questions/369980/can-virtualboxs-tools-automatically-hide-the-windows-taskbar-for-seamless-mode

Virtualbox Network settings:

https://www.nakivo.com/blog/virtualbox-network-setting-guide/

https://petri.com/how-to-improve-network-performance-in-windows-virtualbox-guests

https://www.virtualbox.org/manual/ch03.html

https://superuser.com/questions/286722/what-would-be-optimal-settings-for-a-windows-7-virtualbox-vm-running-on-a-macboo

Application to notify user of active VNC connection:

https://apple.stackexchange.com/questions/15945/application-to-notify-user-of-active-vnc-connection

Move windows to specific screens using the command line:

https://askubuntu.com/questions/702071/move-windows-to-specific-screens-using-the-command-line

Save/Restore window positions:

https://lists.luv.asn.au/pipermail/luv-main/2018-July/010423.html

Deviation of wmctrl windows move command:

https://askubuntu.com/questions/576604/what-causes-the-deviation-in-the-wmctrl-window-move-command

How to safely shutdown Guest OS in VirtualBox using command line

https://askubuntu.com/questions/42482/how-to-safely-shutdown-guest-os-in-virtualbox-using-command-line

Mount Virtualbox Drive Image:

https://linux.m2osw.com/mounting-vdi-disk-your-host-system-edit-file-system

https://askubuntu.com/questions/19430/mount-a-virtualbox-drive-image-vdi