So, now Chrome (35+) and FireFox don't support GWT "classic" DevMode, I've managed to run drools-wb in SuperDevMode. 

The "classic" DevMode will not be supported in GWT 2.6:

Here's my findings on how to configure your webapp, IDE and run (or debug) the damn thing.

These instructions are for IDEA (NetBeans will probably follow a similar route).

(1) Create a regular GWT Launcher:

(2) Create a new GWT Launcher for SuperDevmode:

(3) Add the following to your webapp's gwt.xml (module) file:

  <!-- SuperDevMode -->
  <add-linker name="xsiframe"/>
  <set-configuration-property name="devModeRedirectEnabled" value="true"/>
  <set-property name="compiler.useSourceMaps" value="true"/>
  <set-configuration-property name='xsiframe.failIfScriptTag' value='false'/>

(4) Launch your regular webapp (the "classic" GWT Launcher):

... <tick>, <tock>, <tick>, <tock> while it compiles and launches...

(5) Launch the SuperDevMode code server (the "SuperDevMode" GWT Launcher):

... <tick>, <tock>, <tick>, <tock> while it compiles and launches...

​(6) Drag the "Dev Mode On" and "Dev Mode Off" buttons to your bookmark bar (as advised) - but we don't normally read these sort of things, right! ;)

(7) Go back to the webapp's browser tab

(8) Click on the "Dev Mode On" bookmark you created in step (6)

(9) Click on "compile"

(10) Delete the "codesvr" part of the URL and press enter (dismiss the popups that appear; which ones depends on what browser your GWT module targets; e.g. I had to dismiss a popup about using Chrome but the GWT model targets FireFox).

​(11) Done!

(12) What's that? You want to debug your application?!?

This isn't too bad. Just launch both your "classic" GWT Launcher in debug mode and the "SuperDevMode" GWT Launcher in normal mode.

Server-side code needs break-points in IDEA, and client-side break-points need to be added using Chrome's Developer Tools (you'll need to make sure "sourceMaps" are enabled, but this appears to be the default in Chrome 35).

Accessing Chrome's debugger:



It takes a bit of getting used to debugging client-side stuff in Chrome, and server-side stuff in IDEA, but it's not terrible (although don't expect to be able to introspect everything in Chrome like you used to in IDEA).

I hope this helps (probably more so as others find "DevMode" stops working for them.... and when we move to GWT 2.6.1 --- for IE10 support --- so it is coming sooner than later).