GUI: better thread-safety in the MainWindow + fixed a bug where you could close the 'Closing debugger...' window

x64_dbg_gui/Project/Src/Gui/CloseDialog.cpp

@@ -14,3 +14,8 @@ CloseDialog::~CloseDialog()
 {
     delete ui;
 }
+
+void CloseDialog::closeEvent(QCloseEvent* event)
+{
+    event->ignore();
+}

x64_dbg_gui/Project/Src/Gui/CloseDialog.h

@@ -2,6 +2,7 @@
 #define CLOSEDIALOG_H
 
 #include <QDialog>
+#include <QCloseEvent>
 
 namespace Ui
 {
@@ -15,6 +16,7 @@ class CloseDialog : public QDialog
 public:
     explicit CloseDialog(QWidget* parent = 0);
     ~CloseDialog();
+    void closeEvent(QCloseEvent* event);
 
 private:
     Ui::CloseDialog* ui;

x64_dbg_gui/Project/Src/Gui/MainWindow.cpp

@@ -204,10 +204,6 @@ MainWindow::MainWindow(QWidget* parent) : QMainWindow(parent), ui(new Ui::MainWi
 
 DWORD WINAPI MainWindow::closeThread(void* ptr)
 {
-    static bool closing = false;
-    if(closing)
-        return 0;
-    closing = true;
     DbgExit();
     MainWindow* mainWindow = (MainWindow*)ptr;
     mainWindow->bClose = true;
@@ -220,7 +216,12 @@ void MainWindow::closeEvent(QCloseEvent* event)
     hide(); //hide main window
     mCloseDialog->show();
     mCloseDialog->setFocus();
-    CloseHandle(CreateThread(0, 0, closeThread, this, 0, 0));
+    static bool bExecuteThread = true;
+    if(bExecuteThread)
+    {
+        bExecuteThread = false;
+        CloseHandle(CreateThread(0, 0, closeThread, this, 0, 0));
+    }
     if(bClose)
         event->accept();
     else

x64_dbg_gui/Project/Src/main.cpp

@@ -86,5 +86,3 @@ int main(int argc, char* argv[])
     mConfiguration->save(); //save config on exit
     return result;
 }
-
-