Here is how to build the FindBugs Eclipse Plugin:

Install Eclipse
================
1) Download and install Eclipse 3.4.x.
2) Download and install Subclipse plugin for Subversion.
    Chose [Help | Software Updates... | Available Software | Add Site...] and use
    http://subclipse.tigris.org/update_1.4.x as update site url. Select checkboxes
    [Subclipse (required)] and [SVNKit Adapter (optional)} and click [Install...].
3) Restart Eclipse.

Import the projects
====================
4) Choose [File | Import | SVN | Checkout Projects from SVN]. The import wizard opens.
5) In the wizard, proceed as follows:
   a) Choose [Create a new repository location]. Click [Next]
   b) Enter http://findbugs.googlecode.com/svn as url. Click [Next]
   c) Select 3 children of the <trunk> element (hold CTRL key):
        <trunk>
            |
            +- eclipsePlugin
            +- eclipsePlugin-test
            +- findbugs
      Click [Next]
   d) Do not change defaults on the next page. Click [Next]
   e) Choose the workspace location for project sources, e.g. D:\Projects\FBWorkspace.
   f) Click [Finish].
   g) Source code will be checked out from SVN. This can take time, especially with the
      slow Internet connection (~10 MB need to be downloaded first time).
   h) Now you have three new java projects: [findbugs], [findBugsEclipsePlugin] and [findBugsEclipsePlugin-test]

Setup target platform
======================

6) Create /home/user/bin/Eclipse34 directory. Create "plugins" link there pointing to the
    "plugins" directory located in the root of Eclipse 3.4 installation.
7) Set the right target platform in Eclipse. Go to
    [Window | Preferences | Plugin Development | Target Platform]
    and select the "Eclipse 3.4" target platform definition from the list.
    Currently Eclipse 3.4 is still supported, even if Eclipse 3.6 is already released!
    Additional target platforms can be setup in the similar way.
    Under Windows, replace "/home/user/" path to something like C:\Documents\%user%.

Change the code
================
8) You can immediately work with the source code. In Eclipse, make sure that
    [Project | Build Automatically] is enabled (this is default). In this case, after the
    first checkout both projects will be compiled. There must be NO compile errors.

Debug Eclipse from Eclipse
===========================
9) Choose [Run | Debug Configurations... | Eclipse Application | right click | New],
    a new default Eclipse debug configuration will be created. Choose [Debug] button to
    start plugin debugging. You do not need to build anything, if
    [Project | Build Automatically] is enabled. You can change the code during debugging
    (hot code replace is supported).

Test Eclipse from Eclipse
==========================
10) Choose [Run | Run Configurations... | All FindBugs Plugin Tests | Run],
    and all available FindBugs Eclipse plugin tests will be executed. The
    checked in version of tests should not fail with the checked in FindBugs plugin code.

Build executable plug-in
=========================
11) Create local.properties file in the [findBugsEclipsePlugin] root directory.
   The local.properties file must contain the location of
   - Eclipse platform (key is "eclipsePlugin.dir", value is the 3.4+ Eclipse plugins folder,
   see "target platform" step).
   - SVN ant task (key is "svnant.home", value is the svnant 1.2.1 root folder).
   You can download svnant task from http://subclipse.tigris.org/files/documents/906/43359/svnant-1.2.1.zip.
12) Open [Package Explorer] view, expand the project [findBugsEclipsePlugin].
13) Right-click the build.xml file and choose [Run As | Ant Build] from the context menu.
14) You can now watch ANT working in the console view. After a few
    seconds, the console view should print "BUILD SUCCESSFUL".
15) Right click on [findBugsEclipsePlugin] to refresh the Eclipse workspace
    a) In the [findBugsEclipsePlugin]/bin_build folder you will find the file
    edu.umd.cs.findbugs.plugin.eclipse_<version>.<date>.zip which contains zipped plugin.
    b) In the [findBugsEclipsePlugin]/dist folder you will find the contents of the
    FindBugs Eclipse plugin directory as it should be installed in Eclipse.

16) For information on how to install the compiled plug-ins into Eclipse, please refer
to the document "installing_findbugsplugin.txt".