Num keys in Captain mode to switch to given edit tab

1. Num keys 1 - 9 will activate the specified sequence edit tab;
2. Num key 0 will alternate between the current and last tab;

src/vcaptain.cpp

@@ -108,6 +108,39 @@ bool VCaptain::handleKeyPress(int p_key, Qt::KeyboardModifiers p_modifiers)
 
     // In Captain mode, Ctrl key won't make a difference.
     switch (p_key) {
+    case Qt::Key_1:
+    case Qt::Key_2:
+    case Qt::Key_3:
+    case Qt::Key_4:
+    case Qt::Key_5:
+    case Qt::Key_6:
+    case Qt::Key_7:
+    case Qt::Key_8:
+    case Qt::Key_9:
+    {
+        // Switch to tab <i>.
+        VEditWindow *win = m_mainWindow->editArea->getCurrentWindow();
+        if (win) {
+            int sequence = p_key - Qt::Key_0;
+            if (win->activateTab(sequence)) {
+                m_widgetBeforeCaptain = NULL;
+            }
+        }
+        break;
+    }
+
+    case Qt::Key_0:
+    {
+        // Alternate the tab.
+        VEditWindow *win = m_mainWindow->editArea->getCurrentWindow();
+        if (win) {
+            if (win->alternateTab()) {
+                m_widgetBeforeCaptain = NULL;
+            }
+        }
+        break;
+    }
+
     case Qt::Key_D:
         // Locate current tab.
         m_mainWindow->locateCurrentFile();

src/veditwindow.cpp

@@ -12,7 +12,8 @@
 extern VConfigManager vconfig;
 
 VEditWindow::VEditWindow(VNote *vnote, VEditArea *editArea, QWidget *parent)
-    : QTabWidget(parent), vnote(vnote), m_editArea(editArea)
+    : QTabWidget(parent), vnote(vnote), m_editArea(editArea),
+      m_curTabWidget(NULL), m_lastTabWidget(NULL)
 {
     initTabActions();
     setupCornerWidget();
@@ -399,9 +400,16 @@ void VEditWindow::handleTabbarClicked(int p_index)
     }
 }
 
-void VEditWindow::handleCurrentIndexChanged(int /* p_index */)
+void VEditWindow::handleCurrentIndexChanged(int p_index)
 {
     focusWindow();
+
+    QWidget *wid = widget(p_index);
+    if (wid && (wid == m_curTabWidget)) {
+        return;
+    }
+    m_lastTabWidget = m_curTabWidget;
+    m_curTabWidget = wid;
 }
 
 void VEditWindow::mousePressEvent(QMouseEvent *event)
@@ -746,3 +754,26 @@ bool VEditWindow::showOpenedFileList()
     leftBtn->showMenu();
     return true;
 }
+
+bool VEditWindow::activateTab(int p_sequence)
+{
+    const int base = 1;
+    if (p_sequence < base || p_sequence >= (base + count())) {
+        return false;
+    }
+    setCurrentIndex(p_sequence - base);
+    return true;
+}
+
+bool VEditWindow::alternateTab()
+{
+    if (m_lastTabWidget) {
+        if (-1 != indexOf(m_lastTabWidget)) {
+            setCurrentWidget(m_lastTabWidget);
+            return true;
+        } else {
+            m_lastTabWidget = NULL;
+        }
+    }
+    return false;
+}

src/veditwindow.h

@@ -50,6 +50,9 @@ public:
     void focusNextTab(bool p_right);
     // Return true if the file list is shown.
     bool showOpenedFileList();
+    bool activateTab(int p_sequence);
+    // Switch to previous activated tab.
+    bool alternateTab();
 
 protected:
     void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
@@ -102,6 +105,11 @@ private:
 
     VNote *vnote;
     VEditArea *m_editArea;
+
+    // These two members are only used for alternateTab().
+    QWidget *m_curTabWidget;
+    QWidget *m_lastTabWidget;
+
     // Button in the right corner
     QPushButton *rightBtn;
     // Button in the left corner