Add page switch feature to main window and now all qt stylesheet are loaded from an external file.

Rename test dialog window to test page.

core_lib/game/version_info.py

@@ -459,7 +459,7 @@ def fetch_and_save_version_manifest(dest: Path, target_version: str=None, root_m
         )
 
 def download_core_file(manifest: dict, destination: Path, is_server=False, raise_for_null_hash=False,
-                       progress_callback: Callable[str]=None) -> FileObject:
+                       progress_callback: Callable[[str, float], None]=None) -> FileObject:
     """
     Download core file from version manifest.
     :param manifest:

core_lib/qt/hack.py

@@ -1,5 +1,5 @@
-from PySide6.QtCore import QCoreApplication, QThread
-from PySide6.QtGui import QScreen
+from PySide6.QtCore import QCoreApplication, QThread, QSize, Qt
+from PySide6.QtGui import QScreen, QPixmap, QPainter, QPalette, QIcon
 from PySide6.QtWidgets import QMainWindow, QApplication
 
 
@@ -12,4 +12,24 @@ def move_window_to_center(window: QMainWindow):
 
 def is_main_thread() -> bool:
     app = QCoreApplication.instance()
-    return app is not None and QThread.currentThread() == app.thread()
+    return app is not None and QThread.currentThread() == app.thread()
+
+def recolor_standard_icon(widget, standard_pixmap, size=24):
+    source_icon = widget.style().standardIcon(standard_pixmap)
+    source = source_icon.pixmap(QSize(size, size))
+
+    result = QPixmap(source.size())
+    result.fill(Qt.GlobalColor.transparent)
+
+    painter = QPainter(result)
+    painter.drawPixmap(0, 0, source)
+    painter.setCompositionMode(
+        QPainter.CompositionMode.CompositionMode_SourceIn
+    )
+    painter.fillRect(
+        result.rect(),
+        widget.palette().color(QPalette.ColorRole.ButtonText),
+    )
+    painter.end()
+
+    return QIcon(result)