The cursor isn't blinking, the cursor follows the mouse movements... What you want to stop blinking is the caret, marking the insertion point. I am making this point because knowing the right term allows to search the preferences.txt file!
Close the PDE and in the above mentioned file, search editor.caret.blink. Set it to false, and run the PDE to see if it works.

Hi phi.lho,

Thanks for your reply. I found C:\Program Files\processing-1.5.1\lib\preference.txt and searched for editor.caret.blink but can't find it in that file. Below is my file preference.txt. I wonder what I'm doing wrong.

Thanks for your help,

Shane

1. # !!!!!!!! UNLIKE PREVIOUS VERSIONS OF PROCESSING !!!!!!!!!!
   # DO NOT MODIFY THIS FILE, OR DELETE SETTINGS FROM THIS FILE
   
   # These are the default preferences. If you want to modify
   # them directly, use the per-user local version of the file:
   
   # Documents and Settings -> [username] -> Application Data ->
   #    Processing -> preferences.txt (on Windows XP)
   
   # Users -> [username] -> AppData -> Roaming ->
   #    Processing -> preferences.txt (on Windows Vista)
   
   # ~/Library -> Processing -> preferences.txt (on Mac OS X)
   
   # ~/.processing -> preferences.txt (on Linux)
   
   # The exact location of your preferences file can be found at
   # the bottom of the Preferences window inside Processing.
   
   # Because AppData and Application Data may be considered
   # hidden or system folders on Windows, you'll have to ensure
   # that they're visible in order to get at preferences.txt
   
   # You'll have problems running Processing if you incorrectly
   # modify lines in this file.
   
   
   # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
   
   
   # DEFAULT PATHS FOR SKETCHBOOK AND SETTINGS
   
   # relative paths will be relative to processing.exe or procesing.app.
   # absolute paths may also be used.
   
   # note that this path should use forward slashes (like unix)
   # instead of \ on windows or : on macos or whatever else
   
   # If you don't want users to have their sketchbook default to
   # "My Documents/Processing" on Windows and "Documents/Processing" on OS X,
   # set this to another path that will be used by default.
   # Note that this path must exist already otherwise it won't see
   # the sketchbook folder, and will instead assume the sketchbook
   # has gone missing, and that it should instead use the default.
   #sketchbook.path=
   
   # if you don't want settings to go into "application data" on windows
   # and "library" on macosx, set this to the alternate location.
   #settings.path=data
   
   # By default, no sketches currently open
   last.sketch.count=0
   
   # true if you want sketches to re-open when you next run processing
   last.sketch.restore=true
   
   
   # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
   
   
   # by default, check the processing server for any updates
   # (please avoid disabling, this also helps us know basic numbers
   # on how many people are using Processing)
   update.check = true
   
   # on windows, automatically associate .pde files with processing.exe
   platform.auto_file_type_associations = true
   
   # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
   
   
   # default size for the main window
   editor.window.width.default = 500
   editor.window.height.default = 600
   
   editor.window.width.min = 400
   editor.window.height.min = 500
   # tested as approx 440 on OS X
   editor.window.height.min.macosx = 450
   # tested to be 515 on Windows XP, this leaves some room
   editor.window.height.min.windows = 530
   
   # font size for editor
   editor.font=Monospaced,plain,12
   # Monaco is nicer on Mac OS X, so use that explicitly
   editor.font.macosx = Monaco,plain,10
   
   # anti-aliased text, turned off by default
   editor.antialias=false
   # linux fonts are hideous without anti-aliasing [0191]
   editor.antialias.linux=true
   
   # currently using an external editor
   editor.external=false
   
   # enable ctrl-ins, shift-ins, shift-delete for cut/copy/paste
   # on windows and linux, but disable on the mac
   editor.keys.alternative_cut_copy_paste = true
   editor.keys.alternative_cut_copy_paste.macosx = false
   
   # true if shift-backspace sends the delete character,
   # false if shift-backspace just means backspace
   editor.keys.shift_backspace_is_delete = true
   
   # home and end keys should only travel to the start/end of the current line
   editor.keys.home_and_end_travel_far = false
   # the OS X HI Guidelines say that home/end are relative to the document
   # if you don't like it, this is the preference to change
   editor.keys.home_and_end_travel_far.macosx = true
   
   # font choice and size for the console
   console.font = Monospaced,plain,11
   console.font.macosx = Monaco,plain,10
   
   # number of lines to show by default
   console.lines = 4
   
   # set to false to disable automatically clearing the console
   # each time 'run' is hit
   console.auto_clear = true
   
   # set the maximum number of lines remembered by the console
   # the default is 500, lengthen at your own peril
   console.length = 500
   
   # convert tabs to spaces? how many spaces?
   editor.tabs.expand = true
   editor.tabs.size   = 2
   
   # automatically indent each line
   editor.indent = true
   
   # size of divider between editing area and the console
   editor.divider.size = 0
   # the larger divider on windows is ugly with the little arrows
   # this makes it large enough to see (mouse changes) and use,
   # but keeps it from being annoyingly obtrusive
   editor.divider.size.windows = 2
   
   # any additional java options when running externally
   # (for applets that are run external to the environment...
   # those with a code folder, or using any libraries)
   # if you hose this and can't run things, it's your own durn fault
   run.options =
   
   # settings for the -XmsNNNm and -XmxNNNm command line option
   run.options.memory = false
   run.options.memory.initial = 64
   run.options.memory.maximum = 256
   
   # example of increasing the memory size for applets run externally
   #run.options = -Xms128m -Xmx1024m
   
   # index of the default display to use for present mode
   # (this setting not yet completely implemented)
   run.display = 1
   
   # set internally
   #run.window.bgcolor=
   
   # set to false to open a new untitled window when closing the last window
   # (otherwise, the environment will quit)
   # default to the relative norm for the different platforms,
   # but the setting can be changed in the prefs dialog anyway
   #sketchbook.closing_last_window_quits = true
   #sketchbook.closing_last_window_quits.macosx = false
   
   editor.untitled.prefix=sketch_
   # old (pre-1.0) style for default sketch name
   #editor.untitled.suffix=yyMMdd
   # new (1.0) style for sketch naming. if you change this, be sure that
   # this will work with your language settings. for instance, MMMdd won't work
   # on Korean-language systems because it will insert non-ascii characters.
   # http://code.google.com/p/processing/issues/detail?id=283
   #editor.untitled.suffix=MMMdd
   
   
   # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
   
   
   #history.recording = true
   
   # for advanced users, enable option to export a library
   #export.library = false
   
   # which platforms to export by default
   export.application.platform.windows = true
   export.application.platform.macosx = true
   export.application.platform.linux = true
   
   # whether or not to export as full screen (present) mode
   export.application.fullscreen = false
   
   # whether to show the stop button when exporting to application
   export.application.stop = true
   
   # false will place all exported files into a single .jar
   export.applet.separate_jar_files = false
   
   # set to false to no longer delete applet or application folders before export
   export.delete_target_folder = true
   
   # may be useful when attempting to debug the preprocessor
   preproc.save_build_files=false
   
   # allows various preprocessor features to be toggled
   # in case they are causing problems
   
   # preprocessor: pde.g
   preproc.color_datatype = true
   preproc.web_colors = true
   preproc.enhanced_casting = true
   
   # preprocessor: PdeEmitter.java
   preproc.substitute_floats = true
   #preproc.substitute_image = false
   #preproc.substitute_font = false
   
   # auto-convert non-ascii chars to unicode escape sequences
   preproc.substitute_unicode = true
   
   # PdePreproc.java
   # writes out the parse tree as parseTree.xml, which can be usefully
   # viewed in (at least) Mozilla or IE.  useful when debugging the preprocessor.
   preproc.output_parse_tree = false
   
   # Changed after 1.0.9 to a new name, and also includes the specific entries
   preproc.imports.list = java.applet.*,java.awt.Dimension,java.awt.Frame,java.awt.event.MouseEvent,java.awt.event.KeyEvent,java.awt.event.FocusEvent,java.awt.Image,java.io.*,java.net.*,java.text.*,java.util.*,java.util.zip.*,java.util.regex.*
   
   # set to the program to be used for opening HTML files, folders, etc.
   #launcher.linux = xdg-open
   
   # FULL SCREEN (PRESENT MODE)
   run.present.bgcolor = #666666
   run.present.stop.color = #cccccc
   # starting in release 0159, don't use full screen exclusive anymore
   run.present.exclusive = false
   # use this by default to hide the menu bar and dock on osx
   run.present.exclusive.macosx = true
   
   

you have two preferences.txt files on your system (at least i do).
the one you need should be somewhere here:
C:\Documents and Settings\user\application data\processing\preferences.txt



edit:
you can find the path, when you
-> open the processing IDE
-> File
-> Preferences
-> and click on the link on the bottom of the Preferences-window

Hi Thomas,

I found the new preference file but there is no editor.caret.blink in it. Here's the new file below.

1. update.id=3979154317125324690
   export.application.platform.windows=true
   preproc.save_build_files=false
   preproc.substitute_floats=true
   run.options=
   console.font=Monospaced,plain,11
   editor.window.width.min=400
   run.display=1
   editor.divider.size=2
   preproc.enhanced_casting=true
   editor.divider.size.windows=2
   editor.font=Monospaced,plain,12
   console.auto_clear=true
   last.sketch.mode=processing.mode.java.JavaMode
   editor.keys.home_and_end_travel_far.macosx=true
   last.sketch.count=0
   editor.window.height.min=530
   export.application.platform=true
   editor.keys.alternative_cut_copy_paste.macosx=false
   export.application.stop=true
   editor.window.height.min.macosx=450
   preproc.output_parse_tree=false
   editor.external=false
   editor.indent=true
   last.screen.height=768
   run.present.bgcolor=#666666
   preproc.web_colors=true
   editor.tabs.expand=true
   run.present.stop.color=#cccccc
   preproc.color_datatype=true
   last.screen.width=1366
   editor.keys.shift_backspace_is_delete=true
   editor.window.height.min.windows=530
   export.application.platform.linux=true
   export.application.platform.macosx=true
   export.applet.separate_jar_files=false
   editor.antialias=false
   editor.tabs.size=2
   preproc.substitute_unicode=true
   editor.antialias.linux=true
   run.present.exclusive.macosx=true
   console.lines=4
   run.options.memory.maximum=256
   console.font.macosx=Monaco,plain,10
   update.check=true
   last.sketch0.path=C:\Users\Bro\Documents\Processing\MySinWave\MySinWave.pde
   run.window.bgcolor=#F0F0F0
   editor.keys.home_and_end_travel_far=false
   sketchbook.path=C:\Users\Bro\Documents\Processing
   last.sketch0.location=433,84,500,600,416
   editor.keys.alternative_cut_copy_paste=true
   update.last=1314133003187
   export.delete_target_folder=true
   platform.auto_file_type_associations=false
   editor.window.width.default=500
   run.options.memory.initial=64
   preproc.imports.list=java.applet.*,java.awt.Dimension,java.awt.Frame,java.awt.event.MouseEvent,java.awt.event.KeyEvent,java.awt.event.FocusEvent,java.awt.Image,java.io.*,java.net.*,java.text.*,java.util.*,java.util.zip.*,java.util.regex.*
   run.options.memory=false
   export.application.fullscreen=false
   last.sketch.restore=true
   editor.font.macosx=Monaco,plain,10
   editor.window.height.default=600
   console.length=500
   run.present.exclusive=false
   editor.untitled.prefix=sketch_
   
   

Thanks,

Shane

I also tried putting an extra line on the end of the file

editor.caret.blink=false

and restarted IDE, but it didn't work

Shane

Ah, perhaps I got this property from older versions of Processing. So it might be obsolete, alas.

Oh no, so it can't be changed, well not easily. I hate blinking cursors or should I say carets!