[ui] removed the 'x' button from the prepare dialog

CHANGELOG.md

@@ -28,6 +28,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
     
 ### UI
 - Changed the **Installed** button color
+- Removed the **x** button from some windows
     
 ## [0.9.0] - 2020-04-15
 ### Features

bauh/view/qt/prepare.py

@@ -116,6 +116,7 @@ class PreparePanel(QWidget, TaskManager):
 
     def __init__(self, context: ApplicationContext, manager: SoftwareManager, screen_size: QSize,  i18n: I18n, manage_window: QWidget):
         super(PreparePanel, self).__init__()
+        self.setWindowFlag(Qt.WindowCloseButtonHint, False)
         self.i18n = i18n
         self.context = context
         self.manage_window = manage_window