Merge pull request #2336 from element-hq/dbkr/doc_debugging

Add docs for debugging element desktop

docs/SUMMARY.md

@@ -6,6 +6,7 @@
 
 - [Native Node modules](native-node-modules.md)
 - [Windows requirements](windows-requirements.md)
+- [Debugging](debugging.md)
 - [Using gdb](gdb.md)
 
 # Distribution

docs/debugging.md

@@ -0,0 +1,28 @@
+# Debugging Element-Desktop
+
+There are two parts of the desktop app that you might want to debug.
+
+## The renderer process
+
+This is the regular element-web codeand can be debugged by just selecting 'toggle developer tools'
+from the menu, even on ppackaged builds. This then works the same as chrome dev tools for element web.
+
+## The main process
+
+This is debugged as a node app, so:
+
+1.  Open any chrome dev tools window
+1.  Start element with the `--inspect-brk` flag
+1.  Notice that you now have a little green icon in the top left of your chrome devtools window, click it.
+
+You are now debugging the code of the desktop app itself.
+
+## The main process of a package app
+
+When the app is shipped, electron's "fuses" are flipped, editing the electron binary itself to prevent certain features from being usable, one of which is debugging using `--inspect-brk` as above. You can flip the fuse back on Linux as follows:
+
+```
+sudo npx @electron/fuses write --app /opt/Element/element-desktop EnableNodeCliInspectArguments=on
+```
+
+A similar command will work, in theory, on mac and windows, except that this will break code signing (which is the point of fuses) so you would have to re-sign the app or somesuch.