Based on discussion http://wpftoolkit.codeplex.com/discussions/447813#post1069463
DecimalUpDown seems to be ignoring MouseWheelActiveOnFocus property. The mousewheel is only active when the mouse pointer is on the control irrespective of this setting.
"MouseWheelActiveOnFocus" property is now obsolete, but the same problem occurs with "MouseWheelActiveTrigger" property :
When focus is on the DecimalUpDown (with MouseWheelActiveTrigger = Focused), and mouse pointer is outside the DecimalUpDown, using the mouseWheel does nothing. If the mouse pointer is over the DecimalUpDown, using the mouseWheel increments/decrements.
It looks like ButtonSpinner.OnMouseWheel() is only called when mouse is over the Control.
Comments: ** Comment from web user: BoucherS **
DecimalUpDown seems to be ignoring MouseWheelActiveOnFocus property. The mousewheel is only active when the mouse pointer is on the control irrespective of this setting.
"MouseWheelActiveOnFocus" property is now obsolete, but the same problem occurs with "MouseWheelActiveTrigger" property :
When focus is on the DecimalUpDown (with MouseWheelActiveTrigger = Focused), and mouse pointer is outside the DecimalUpDown, using the mouseWheel does nothing. If the mouse pointer is over the DecimalUpDown, using the mouseWheel increments/decrements.
It looks like ButtonSpinner.OnMouseWheel() is only called when mouse is over the Control.
Comments: ** Comment from web user: BoucherS **
Correction.
This is not a bug.
Here is the behavior with MouseWheelActiveTrigger on a UpDown control:
a) MouseWheelActiveTrigger = Focused
The control have to be focused and the mouse have to be over the control to increment/decrement.
b) MouseWheelActiveTrigger = MouseOver
The mouse have to be over the control to increment/decrement
c) MouseWheelActiveTrigger = Disabled
The control can't increment/decrement
To prevent misunderstanding, the enum "Focused" will be renamed "FocusedMouseOver" in v2.2.