exe-fix-v4

v2.5.1 + fix width computation on IE + fix display of scroll bar

exe-fix-v3

Fix wrong computation of text area width when scroll bar is visible

exe-fix-v2: Bug fix: include padding attributes for the mirror textarea

The mirror text area is a copy of the original text area and determines whether the scroll bar must be shown. This commit fixes the problem that the scroll bar was not shown even if it should (borderline case)