Wallet encryption part 2: ask passphrase when needed, add menu options

src/qt/askpassphrasedialog.h

@@ -0,0 +1,40 @@
+#ifndef ASKPASSPHRASEDIALOG_H
+#define ASKPASSPHRASEDIALOG_H
+
+#include <QDialog>
+
+namespace Ui {
+    class AskPassphraseDialog;
+}
+
+class WalletModel;
+
+class AskPassphraseDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    enum Mode {
+        Encrypt,    // Ask passphrase x2
+        Unlock,     // Ask passphrase
+        ChangePass, // Ask old passphrase + new passphrase x2
+        Decrypt   // Ask passphrase
+    };
+
+    explicit AskPassphraseDialog(Mode mode, QWidget *parent = 0);
+    ~AskPassphraseDialog();
+
+    void accept();
+
+    void setModel(WalletModel *model);
+
+private:
+    Ui::AskPassphraseDialog *ui;
+    Mode mode;
+    WalletModel *model;
+
+private slots:
+    void textChanged();
+};
+
+#endif // ASKPASSPHRASEDIALOG_H