Dispvm 4.0 updates

Sourced primarily from https://github.com/QubesOS/qubes-issues/issues/2253 and https://groups.google.com/forum/?_escaped_fragment_=topic/qubes-devel/UGh8NDdkrXo#!topic/qubes-devel/UGh8NDdkrXo

common-tasks/dispvm.md

@@ -20,7 +20,31 @@ Once a DispVM has been created it will appear in Qubes VM Manager with the name
 
 See [this article](https://blog.invisiblethings.org/2010/06/01/disposable-vms.html) for more on why one would want to use a Disposable VM.
 
-Disposable VMs and Networking
+Disposable VMs and Networking (R4.0 and later)
+-----------------------------
+
+
+R4.0 introduces the concept of multiple disposable VM templates (R3.2 was limited to one).
+This allows for the creation of multiple differently configured disposable VMs that can be accessed from 
+the Applications menu (e.g. `fedora-XX-dvm`). Even more types of DispVMs can be created on-the-fly on a per AppVM basis.
+As you can see, this is a very flexible and powerful system for managing your Disposable VMs.
+
+NetVM and firewall rules for Disposable VMs can be set as they can for a normal VM. 
+By default a DispVM will inherit the NetVM and firewall settings of the DispVM Template from which it is built. 
+Thus if an AppVM uses sys-net as its NetVM, but the default system DispVM uses sys-whonix,
+any DispVM launched from this AppVM will have sys-whonix as its NetVM.
+The default system wide DispVM template can be changed with `qubes-prefs default_dispvm`.
+You can change this behaviour for individual VMs: in the Application Menu, open Qube Settings
+for the VM in question and go to the "Advanced" tab. 
+Here you can edit the "Default DispVM" setting to specify which DispVM template will be used to launch DispVMs from that VM.
+Disposable VMs will temporarily appear with the name `disp####`. 
+
+A Disposable VM launched from the Start Menu inherits the NetVM and firewall settings of the [DVM Template](https://www.qubes-os.org/doc/glossary/#dvm-template) from which it is built. 
+By default the DVM template is called `fedora-XX-dvm` (where `XX` is the Fedora version of the default TemplateVM). 
+As an "internal" VM it is hidden in Qubes VM Manager, but can be shown by selecting "Show/Hide internal VMs". 
+Note that changing the "NetVM" setting for the DVM Template *does* affect the NetVM of DispVMs launched from the Start Menu.
+
+Disposable VMs and Networking (R3.2 and earlier)
 -----------------------------
 
 NetVM and firewall rules for Disposable VMs can be set as they can for a normal VM. 
@@ -49,7 +73,7 @@ Opening a fresh web browser instance in a new Disposable VM
 -----------------------------------------------------------
 
 Sometimes it is desirable to open an instance of Firefox within a new fresh Disposable VM. 
-This can be done easily using the Start Menu: just go to Start -\> System Tools -\> DispVM:Firefox web browser. 
+This can be done easily using the Start Menu: just go to **Application Menu -\> DisposableVM -\> DispVM:Firefox web browser**. 
 Wait a few seconds until a web browser starts. 
 Once you close the viewing application the whole Disposable VM will be destroyed. 
 
@@ -75,7 +99,7 @@ Sometimes it can be useful to start an arbitrary program in a DispVM. This can b
 [user@vault ~]$ qvm-run '$dispvm' xterm
 ~~~
 
-The created Disposable VM can be accessed via other tools (such as `qvm-copy-to-vm`) using its "dispX" name as shown in the Qubes Manager or `qvm-ls`.
+The created Disposable VM can be accessed via other tools (such as `qvm-copy-to-vm`) using its `disp####` name as shown in the Qubes Manager or `qvm-ls`.
 
 Starting an arbitrary application in a Disposable VM via command line (from Dom0)
 ---------------------------------------------------------------------------------
@@ -83,6 +107,12 @@ Starting an arbitrary application in a Disposable VM via command line (from Dom0
 The Start Menu has shortcuts for opening a terminal and a web browser in dedicated DispVMs, since these are very common tasks.
 However, it is possible to start an arbitrary application in a DispVM directly from Dom0 by running
 
+R4.0 (border colour will be inherited from that set in the `dispvm-template`)
+~~~
+[joanna@dom0 ~]$ qvm-run --dispvm=dispvm-template --service qubes.StartApp+xterm
+~~~
+
+R3.2 (border colour can be specified in the command)
 ~~~
 [joanna@dom0 ~]$ echo xterm | /usr/lib/qubes/qfile-daemon-dvm qubes.VMShell dom0 DEFAULT red
 ~~~
@@ -92,8 +122,8 @@ However, it is possible to start an arbitrary application in a DispVM directly f
 Customizing Disposable VMs
 --------------------------
 
-You can change the template used to generate the Disposable VM, and change settings used in the Disposable VM savefile. 
+You can change the template used to generate the Disposable VMs, and change settings used in the Disposable VM savefile. 
-These changes will be reflected in every new Disposable VM. 
+These changes will be reflected in every new Disposable VM spawned from that template. 
 Full instructions can be found [here](/doc/dispvm-customization/).
 
 Disposable VMs and Local Forensics