Added March 2015; see History
This field allows the application to control the horizontal scroll position on entering the tree.
The field acts analogously to XTR.TOPINDEX, substituting the left-most visible column for the top-most visible row. When set by the application, XTREE will attempt to set the horizontal scroll so that the specified column (first column = 1) is visible at the left edge of the display window. This however will be overridden if necessary to make the target column (XTR.TARGCOL) visible, or if it is simply impossible to accommodate.
As with XTR.TOPINDEX, if the XTR.LEFTINDEX field is non-zero on entrance, it will be updated on exit to indicate the left-most column that is partially or wholly visible on exiting the tree. Since the field resolution doesn't support fractional columns, this may result in a partial-column shift when exiting and re-entering. You can avoid that by either setting the field back to zero, or specifying the XTF_NOREDRAW flag.
History
2015 March, A-Shell 6.1.1306: Field added to A-Shell
