Documentation
Publicon
Reference
Preferences
Notebook Options
PrivateNotebookOptions->{...}
"RealTimeMarginAdjustment"
• "RealTimeMarginAdjustment" is an option for notebooks that determines if the size of margins in a notebook is adjusted in real time when the margin settings are changed by dragging the tab on the ruler toolbar.
• With the setting "RealTimeMarginAdjustment" 
True, cells are adjusted and re-drawn in real time as the margin is adjusted. This allows you to see exactly where word wrapping will occur as the adjustment is made. However, it may be unacceptably slow in some situations.
• With the default setting "RealTimeMarginAdjustment" False, the margins are adjusted only after you finish dragging the tab on the ruler toolbar.
