qt: try another way

src/qt/qt_hardwarerenderer.cpp

@@ -46,7 +46,9 @@ void HardwareRenderer::initializeGL()
 {
     m_context->makeCurrent(this);
     initializeOpenGLFunctions();
-    m_texture = new QOpenGLTexture(QImage(2048,2048, QImage::Format::Format_RGB32));
+    auto image = QImage(2048, 2048, QImage::Format_RGB32);
+    image.fill(0xff000000);
+    m_texture = new QOpenGLTexture(image);
     m_blt = new QOpenGLTextureBlitter;
     m_blt->setRedBlueSwizzle(true);
     m_blt->create();
@@ -138,6 +140,7 @@ void HardwareRenderer::initializeGL()
     pclog("OpenGL shader language version: %s\n", glGetString(GL_SHADING_LANGUAGE_VERSION));
     glClearColor(0, 0, 0, 1);
     m_texture->setWrapMode(QOpenGLTexture::ClampToEdge);
+    update();
 }
 
 void HardwareRenderer::paintGL() {

src/qt/qt_mainwindow.cpp

@@ -507,15 +507,6 @@ MainWindow::MainWindow(QWidget *parent) :
 #endif
     if (!vnc_enabled) video_setblit(qt_blit);
 
-    if (start_in_fullscreen) {
-        connect(ui->stackedWidget, &RendererStack::blit, this, [this] () {
-            if (start_in_fullscreen) {
-                QTimer::singleShot(100, ui->actionFullscreen, &QAction::trigger);
-                start_in_fullscreen = 0;
-            }
-        });
-    }
-
 #ifdef MTR_ENABLED
     {
         ui->actionBegin_trace->setVisible(true);
@@ -711,6 +702,10 @@ void MainWindow::showEvent(QShowEvent *event) {
         QApplication::processEvents();
         this->adjustSize();
     }
+    if (start_in_fullscreen) {
+        start_in_fullscreen = 0;
+        QTimer::singleShot(0, ui->actionFullscreen, &QAction::trigger);
+    }
 }
 
 void MainWindow::on_actionKeyboard_requires_capture_triggered() {

src/qt/qt_openglrenderer.cpp

@@ -14,6 +14,7 @@
  *      Copyright 2022 Teemu Korhonen
  */
 
+#include <GL/gl.h>
 #include <QCoreApplication>
 #include <QMessageBox>
 #include <QOpenGLShaderProgram>
@@ -194,6 +195,9 @@ OpenGLRenderer::initialize()
 
         emit initialized();
 
+        glClear(GL_COLOR_BUFFER_BIT);
+
+        context->swapBuffers(this);
     } catch (const opengl_init_error &e) {
         /* Mark all buffers as in use */
         for (auto &flag : buf_usage)

src/qt/qt_rendererstack.cpp

@@ -416,6 +416,7 @@ RendererStack::createRenderer(Renderer renderer)
     current->setFocusPolicy(Qt::NoFocus);
     current->setFocusProxy(this);
     current->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
+    current->setStyleSheet("background-color: black");
     addWidget(current.get());
 
     this->setStyleSheet("background-color: black");