ichMaxSel (USHORT)
The ichMinSel and ichMaxSel parameters identify the current selection within the entry field control. Characters within the text with byte offsets less than the ichMaxSel parameter and greater than or equal to the ichMinSel parameter are the current selection. The cursor is positioned immediately before the character identified by the ichMaxSel parameter.
If the ichMinSel parameter is equal to the ichMaxSel parameter, the current selection becomes the insertion point.
If the ichMinSel parameter is equal to 0 and the ichMaxSel is greater than or equal to text limit set by the EM_SETTEXTLIMIT message, the entire text is selected.