Merge #14879: qt: Add warning messages to the debug window

593ba696fb Add warning messages to the debug window (Hennadii Stepanov)

Pull request description:

  Fix: #11016

  This PR adds warning messages to the debug window in `-disablewallet` mode.

  ![screenshot from 2018-12-06 01-01-27](https://user-images.githubusercontent.com/32963518/49550070-413c1c80-f8f3-11e8-9865-efb49ea8da45.png)

ACKs for top commit:
  jonasschnelli:
    utACK 593ba696fb
  promag:
    ACK 593ba696fb, agree with @Sjors https://github.com/bitcoin/bitcoin/pull/14879#pullrequestreview-196433092 above.
  ryanofsky:
    utACK 593ba696fb

Tree-SHA512: a8ca78529bb16813ba7bfaf5ccd4349189979f08e78ea857746a6fb00fd9d7ed98d8f06f384830acba21dac57070060af23f6be8249398feb32a6efff1333de8

src/qt/overviewpage.cpp

@@ -204,9 +204,8 @@ void OverviewPage::updateWatchOnlyLabels(bool showWatchOnly)
 void OverviewPage::setClientModel(ClientModel *model)
 {
     this->clientModel = model;
-    if(model)
-    {
-        // Show warning if this is a prerelease version
+    if (model) {
+        // Show warning, for example if this is a prerelease version
         connect(model, &ClientModel::alertsChanged, this, &OverviewPage::updateAlerts);
         updateAlerts(model->getStatusBarWarnings());
     }