qt: Add flags to prevent a "What's This" button on Windows OS

src/qt/createwalletdialog.cpp

@@ -9,6 +9,8 @@
 #include <qt/createwalletdialog.h>
 #include <qt/forms/ui_createwalletdialog.h>
 
+#include <qt/guiutil.h>
+
 #include <QPushButton>
 
 CreateWalletDialog::CreateWalletDialog(QWidget* parent) :

src/qt/guiutil.h

@@ -43,6 +43,9 @@ QT_END_NAMESPACE
  */
 namespace GUIUtil
 {
+    // Use this flags to prevent a "What's This" button in the title bar of the dialog on Windows.
+    constexpr auto dialog_flags = Qt::WindowTitleHint | Qt::WindowSystemMenuHint | Qt::WindowCloseButtonHint;
+
     // Create human-readable string from date
     QString dateTimeStr(const QDateTime &datetime);
     QString dateTimeStr(qint64 nTime);

src/qt/receivecoinsdialog.cpp

@@ -8,6 +8,7 @@
 #include <qt/forms/ui_receivecoinsdialog.h>
 
 #include <qt/addresstablemodel.h>
+#include <qt/guiutil.h>
 #include <qt/optionsmodel.h>
 #include <qt/platformstyle.h>
 #include <qt/receiverequestdialog.h>