When clipboard has multiple tabs at the end of text, the tabs are copied only till it reaches end of line in the <textarea>. For example, if the text "xxx yyy " is copied from clipboard to a <textarea> of width 15, tabs that fit till the end of line are copied. Remaining tabs are lost. However, webkit thinks the whole text is copied and the cursor is at the end of the original text. So, you got to use left arrow key few times before cursor gets updated. Use layout test editing\pasteboard\pasting-tabs.html
*** This bug has been marked as a duplicate of 13927 ***