Dear Maintainer, If Side Panel is enabled (Menu -> View -> Side Panel), then it is impossible, or at least extremely difficult to select the first character of the line (colum 1) as the cursor changes to a resize handle for the Side Panel instead. Another way of looking at this problem is that Side Panel's resize edge extends into the document by enough to prevent selections of that start with the first character of a line.
Hey Liban, I confirm this issue here with gedit 3.14.0-2 also. thanks for reporting. maybe as a workaround selecting from right to left helps or enabling display line numbers will be easier. cheers althaser