Fix reparenting issues with layouts

BUGS

@@ -1,17 +1,6 @@
 Bugs
 ====
 
-- Problems since the reparenting commits:
-
-    - QLayout: Attempting to add QLayout "" to StatusBar "StatusBar", which already has a layout
-    - QLayout: Attempting to add QLayout "" to ExceptionCrashDialog "", which already has a layout
-    - Small empty window spawning at start
-
-- QWindowsWindow::setGeometry: Unable to set geometry 5x13+-959+505 on
-  QWidgetWindow/'TextClassWindow'. Resulting geometry:  116x13+-959+505 (frame:
-  8, 30, 8, 8, custom margin: 0, 0, 0, 0, minimum size: 0x0, maximum size:
-  16777215x16777215).
-
 - On doodle, when modifying something on http://doodle.com/create and clicking
   a link to leave the page, the message is suboptimal. Also, with some random
   clicking it's somehow possible to get out of yesno mode.

qutebrowser/widgets/crash.py

@@ -90,9 +90,9 @@ class _CrashDialog(QDialog):
 
         Should be extended by superclass to provide the actual buttons.
         """
-        self._hbox = QHBoxLayout(self)
-        self._hbox.addStretch()
+        self._hbox = QHBoxLayout()
         self._vbox.addLayout(self._hbox)
+        self._hbox.addStretch()
 
     def _set_text_flags(self, obj):
         """Set text interaction flags of a widget to allow link clicking.

qutebrowser/widgets/statusbar/bar.py

@@ -123,7 +123,8 @@ class StatusBar(QWidget):
         self._hbox.setContentsMargins(0, 0, 0, 0)
         self._hbox.setSpacing(5)
 
-        self._stack = QStackedLayout(self)
+        self._stack = QStackedLayout()
+        self._hbox.addLayout(self._stack)
         self._stack.setContentsMargins(0, 0, 0, 0)
 
         self.cmd = Command()
@@ -147,8 +148,6 @@ class StatusBar(QWidget):
         self.prompt.hide_prompt.connect(self._hide_prompt_widget)
         self._hide_prompt_widget()
 
-        self._hbox.addLayout(self._stack)
-
         self.keystring = KeyString()
         self._hbox.addWidget(self.keystring)
 
@@ -158,7 +157,10 @@ class StatusBar(QWidget):
         self.percentage = Percentage()
         self._hbox.addWidget(self.percentage)
 
-        self.prog = Progress()
+        # We add a parent to Progress here because it calls self.show() based
+        # on some signals, and if that happens before it's added to the layout,
+        # it will quickly blink up as independent window.
+        self.prog = Progress(self)
         self._hbox.addWidget(self.prog)
 
     def __repr__(self):