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"Preferences" redirects here. For Wiki Preferences, see Special:Preferences.

VM Preferences (Virtual Machine Preferences) are the advanced configuration settings for the Squeak Virtual Machine. Scratch is completely written in Squeak.

Note Warning: It is highly recommended that you keep all options as they are originally and only modify these options if you consider yourself to be an advanced user of computers. Changing and clicking on options could result in Scratch to be more unstable and undoing the problem can be a very hard, complicated, and time-consuming process, maybe even impossible. The best way to reverse an error like this is to simply re-install Scratch and clear all Squeak virtual machine files.

Accessing the VM Preferences

The VM Preferences options.

In the top left corner of the Scratch window, there is a small Scratch Cat icon. Click it, or right-click the thumbnail (Windows Vista and up) and the bottom option should be "VM Preferences."

This cat will not appear in Linux distributions.


When you mouse over VM Preferences it will give you more options:

Mouse Mapping

  • 1 button mouse: Tell Scratch that you are using a mouse with just one button.
  • 3 button mouse: Tell Scratch that you are using a mouse with three buttons.

Security Settings

  • Allow file access: Allows Scratch to access files from your hard drive, and import them into Scratch.
  • Allow image writes: Allows Scratch to change the file format of any images it imports into Scratch.
  • Allow socket access: Disables Scratch from accessing the internet, which disables Mesh and means you can not upload projects.
Note Note: All these settings are on by default. However, if you turn them off and on again Squeak will give you a serious warning. Ignore this warning.

Display and Sound

  • Use DirectSound: Enables Scratch to use the DirectSound component of DirectX.
  • Use OpenGL(instead of Direct3D): Chooses the graphics library Scratch uses (OpenGL or Direct3D)
  • Defer display update: Stops the display from updating

System Configuration

  • Reduce CPU usage: Reduces the amount of CPU being used by Scratch.
  • Reduce background CPU usage: Reduces the amount of CPU being used by background programs allowing Scratch to operate faster.
  • Thread priority boost: Boosts the priority of threads.

Debug Options

  • Case sensitive files: All files used in Scratch are case sensitive if this option is on. This can cause problems on Windows because it can not handle files in the same directory who's names are the same except for capitalization.
  • Show output console: Shows the output console of Squeak.
  • Show console on errors: Shows the output console whenever there is a script error.
  • Show allocation activity: Shows the allocation activity.
  • Dump network state: Dumps network state information to the output console.
  • Dump call stack: Dumps the current call stack to the output console
  • Dump all processes: Dumps process information to the output console.
  • Display version information: Displays the version of Squeak (version 3.10.10 for Scratch 1.4).
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