some fixes for web spreadsheet keypress shift-select

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35024 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
implemented hide/show web spreadsheet scrollbars

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35025 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e