Aug 20, 2007 - Change the Tab Size in FlexBuilder
To change the default number of spaces when you press the tab key

Flex Builder defaults to using 4 spaces for a tab, to change it:

• Select Window->
• Preferences->
• Flex->
• Editors->
• Tab Size: [4] to whatever you want

There's a similar parameter that may fool you, General->Editors->Text Editors->Displayed tab width