If Op is iespReplace the region replaces the existing selection, otherwise if Op is iespAdd, the region is appended to the existing selection
CheckAlpha
If true, it also considers the AlphaChannel when matching
Note: ◼If SelectionBase = iesbClientArea then x and y are assumed to be visible points on the control. If iesbBitmap, the points specify a position on the bitmap. ◼This is the programmatic equivalent of setting miSelectMagicWand in MouseInteractGeneral ◼MagicWandMode determines the nature of the magic wand selection. For iewInclusive a "vectorized" selection is created (i.e. the selection will be made up of a series of lines and can be accessed via PolySel). For other types a "bitmap" selection is used (to determine whether specific pixels are selected, use IsPointInsideSelection)