Fix stack-overflow when auto-sizing dropdowns.

Fix combobox button click not closing the popup listbox when clicking the button with a visible popup listbox.
Fix some incorrect size policies in UIFileDialog.

include/eepp/ui/uicombobox.hpp

@@ -21,7 +21,7 @@ class EE_API UIComboBox : public UIWidget {
 
 	UIDropDownList* getDropDownList() const { return mDropDownList; }
 
-	UINode* getButton() const { return mButton; }
+	UIWidget* getButton() const { return mButton; }
 
 	const String& getText();
 
@@ -38,7 +38,7 @@ class EE_API UIComboBox : public UIWidget {
 
   protected:
 	UIDropDownList* mDropDownList;
-	UINode* mButton;
+	UIWidget* mButton;
 
 	UIComboBox();
 

include/eepp/ui/uidropdown.hpp

@@ -51,15 +51,24 @@ class EE_API UIDropDown : public UITextInput {
 										   const Uint32& propertyIndex = 0 ) const;
 	virtual std::vector<PropertyId> getPropertiesImplemented() const;
 
+	void addRelatedWidget( UIWidget* widget ) { mRelatedWidgets.push_back( widget ); }
+
+	void removeRelatedWidget( UIWidget* widget ) {
+		mRelatedWidgets.erase(
+			std::find( mRelatedWidgets.begin(), mRelatedWidgets.end(), widget ) );
+	}
+
   protected:
 	StyleConfig mStyleConfig;
 	UINode* mFriendNode{ nullptr };
+	Uint64 mLastFocusLoss{ 0 };
+	std::vector<UIWidget*> mRelatedWidgets;
 
 	UIDropDown( const std::string& tag );
 
 	virtual UIWidget* getPopUpWidget() const;
 
-	void onPopUpFocusLoss( const Event* Event );
+	virtual void onPopUpFocusLoss();
 
 	virtual void onItemSelected( const Event* Event );
 	virtual void show();

include/eepp/ui/uihelper.hpp

@@ -47,6 +47,7 @@ enum UIFlag : Int64 {
 	UI_HTML_ELEMENT = ( 1ULL << 31 ),
 	UI_CREATING_NODE = ( 1ULL << 32 ),
 	UI_IGNORE_GLOBAL_CSS = ( 1ULL << 33 ),
+	UI_AUTO_SIZING = ( 1ULL << 34 ),
 };
 
 enum UINodeType {