Ensure that at least one column in the tranferlist is always visible. Closes #1165.

src/transferlistwidget.cpp

@@ -127,6 +127,17 @@ TransferListWidget::TransferListWidget(QWidget *parent, MainWindow *main_window,
     setColumnHidden(TorrentModelItem::TR_SAVE_PATH, true);
   }
 
+  //Ensure that at least one column is visible at all times
+  bool atLeastOne = false;
+  for (unsigned int i=0; i<TorrentModelItem::NB_COLUMNS; i++) {
+    if (!isColumnHidden(i)) {
+      atLeastOne = true;
+      break;
+    }
+  }
+  if (!atLeastOne)
+    setColumnHidden(TorrentModelItem::TR_NAME, false);
+
   //When adding/removing columns between versions some may
   //end up being size 0 when the new version is launched with
   //a conf file from the previous version.
@@ -558,11 +569,23 @@ void TransferListWidget::displayDLHoSMenu(const QPoint&) {
     myAct->setChecked(!isColumnHidden(i));
     actions.append(myAct);
   }
+  int visibleCols = 0;
+  for (unsigned int i=0; i<TorrentModelItem::NB_COLUMNS; i++) {
+    if (!isColumnHidden(i))
+      visibleCols++;
+
+    if (visibleCols > 1)
+      break;
+  }
+
   // Call menu
   QAction *act = hideshowColumn.exec(QCursor::pos());
   if (act) {
     int col = actions.indexOf(act);
     Q_ASSERT(col >= 0);
+    Q_ASSERT(visibleCols > 0);
+    if (!isColumnHidden(col) && visibleCols == 1)
+      return;
     qDebug("Toggling column %d visibility", col);
     setColumnHidden(col, !isColumnHidden(col));
     if (!isColumnHidden(col) && columnWidth(col) <= 5)