At this page: https://developers.google.com/java-dev-tools/download-wbpro, there is no option to install WindowBuilder Pro to Eclipse Juno (4.2).
Is WindowBuilder Pro already installed with Eclipse Juno?
Also, is there a better free alternative to WindowBuilder Pro?
Note that currently, it is included by default only in the version for Java Developers, NOT in the version for Java EE Developers, which is the most downloaded and wanted version. So for the Eclipse IDE for Java EE Developers you still need to install it yourself.
It is not installed by default in Eclipse.
The new WindowsBuilder Pro home page is here:
On that page, in the "Current Status" section on the right, it says (emphasis mine):
"Welcome to the new WindowBuilder homepage!"
1) Copy the correct link for your version of Eclipse from the Update Site column (Release Version) on the download page:
2) In the Eclipse main menu choose Help > Install new Software...
3) In the appeared window click Add... button:
4) In the appeared dialog box, in the Name field write some descriptive name (like "WindowBuilder Pro") and paste the correct link (see step 1) in the Location field. After that click the OK button:
5) Select all the checkboxes that are going to appear, then click Next button and install WindowBuilder:
Another way to add a link to the list of available Software Sites:
in the Eclipse main menu choose Window > Preferences, in the preferences window choose Install/Update > Available Software Sites, click Add... button and go on as described above.
As for the better alternative, well, seems like WindowBuilder Pro is the most preferred: Best GUI designer for Eclipse?
Hope this helps.