Merge #165: Save QSplitter state in QSettings

90f9fc2 qt: Save QSplitter state in QSettings (Hennadii Stepanov)

Pull request description:

  This PR adds the ability to save the `QSplitter` widget state in `QSettings` during shutdown, and restore it on startup.

  A user no longer needs to adjust the splitter every time :)
  ![DeepinScreenshot_select-area_20201225211422](https://user-images.githubusercontent.com/32963518/103141024-046c3980-46f7-11eb-9a8c-83613527ffe1.png)

ACKs for top commit:
  jonasschnelli:
    utACK 90f9fc2
  jonatack:
    ACK 90f9fc2 this sets the "PeersTabSplitterSizes" value in the RPCConsole dtor and restores it in the RPCConsole ctor; tested in Debian with various split settings, tab open/close sequences, and shutdown methods, and the Peers window split state was faithfully maintained.

Tree-SHA512: efbd6a4cee512982944955d36775e75a8a217b1dc49e62d42c6e402d2710dd44324b2c3c1edeb5fe38d9229e0e4a39734d1f4e63405ade8694762e1bbf72020b

Author: MarcoFalke

src/qt/rpcconsole.cpp

@@ -457,6 +457,8 @@ RPCConsole::RPCConsole(interfaces::Node& node, const PlatformStyle *_platformSty
         move(QGuiApplication::primaryScreen()->availableGeometry().center() - frameGeometry().center());
     }
 
+    ui->splitter->restoreState(settings.value("PeersTabSplitterSizes").toByteArray());
+
     QChar nonbreaking_hyphen(8209);
     ui->dataDir->setToolTip(ui->dataDir->toolTip().arg(QString(nonbreaking_hyphen) + "datadir"));
     ui->blocksDir->setToolTip(ui->blocksDir->toolTip().arg(QString(nonbreaking_hyphen) + "blocksdir"));
@@ -502,6 +504,7 @@ RPCConsole::~RPCConsole()
 {
     QSettings settings;
     settings.setValue("RPCConsoleWindowGeometry", saveGeometry());
+    settings.setValue("PeersTabSplitterSizes", ui->splitter->saveState());
     m_node.rpcUnsetTimerInterface(rpcTimerInterface);
     delete rpcTimerInterface;
     delete ui;