BUG: Set sizepolicy to ctkDirectoryButton

Libs/Widgets/ctkDirectoryButton.cpp

@@ -67,6 +67,7 @@ void ctkDirectoryButtonPrivate::init()
   l->addWidget(this->PushButton);
   l->setContentsMargins(0,0,0,0);
   p->setLayout(l);
+  p->setSizePolicy(QSizePolicy(QSizePolicy::Minimum, QSizePolicy::Fixed, QSizePolicy::ButtonBox));
 }
 
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