indexing - C#: get row back in datagridview (shift+tab) -

i programmatically jump next row pressing tab button. if want jump back, use tab + shift key. if tab + shift pressed, rowcount gets reduced two. when want go last row, index jumps first control, has tab index of 0. whats problem @ last row?

private void datagridview1_keydown(object sender, keyeventargs e)     {         if (e.keycode == keys.tab)         {             int row = datagridview1.currentcell.rowindex;             row++;             if (row > datagridview1.rowcount - 1)             {                 menustrip1.select();                 datensatztoolstripmenuitem.select();                 datagridview1.currentcell = datagridview1[0, 0];             }             else datagridview1.currentcell = datagridview1[0, row];             e.handled = true;         }         if (e.modifiers == keys.shift && e.keycode == keys.tab)         {             int row = datagridview1.currentcell.rowindex;             row -= 2;             if (row < 0)              {                 menustrip1.select();                 datensatztoolstripmenuitem.select();                 datagridview1.currentcell = datagridview1[0, 0];             }             else datagridview1.currentcell = datagridview1[0, row];             e.handled = true;         }     } 

the problem having because both conditions in code met when shift+tab pressed.

the following code works fine on machine.

private void datagridview1_keydown(object sender, keyeventargs e) {     if (e.keycode == keys.tab) {         if (e.modifiers != keys.shift) {             int row = datagridview1.currentcell.rowindex;             row++;             if (row > datagridview1.rowcount - 1) {                 menustrip1.select();                 datensatztoolstripmenuitem.select();                 datagridview1.currentcell = datagridview1[0, 0];             }             else {                 datagridview1.currentcell = datagridview1[0, row];             }             e.handled = true;         }         else {             int row = datagridview1.currentcell.rowindex;             row -= 1;             if (row < 0) {                 menustrip1.select();                 datensatztoolstripmenuitem.select();                 datagridview1.currentcell = datagridview1[0, 0];             }             else {                 datagridview1.currentcell = datagridview1[0, row];             }             e.handled = true;         }     } }