Support GenericBox max height / scroll style.

ui/layers/box_content.cpp

@@ -103,10 +103,6 @@ QPointer<IconButton> BoxContent::addTopButton(
 	return result;
 }
 
-void BoxContent::setInner(object_ptr<TWidget> inner) {
-	setInner(std::move(inner), st::boxScroll);
-}
-
 void BoxContent::setInner(
 		object_ptr<TWidget> inner,
 		const style::ScrollArea &st) {

ui/layers/box_content.h

@@ -31,6 +31,10 @@ struct ScrollArea;
 struct Box;
 } // namespace style
 
+namespace st {
+extern const style::ScrollArea &boxScroll;
+} // namespace st
+
 namespace Ui {
 class GenericBox;
 } // namespace Ui
@@ -242,11 +246,11 @@ protected:
 			object_ptr<Widget> inner,
 			int topSkip = 0,
 			int bottomSkip = 0) {
-		auto result = QPointer<Widget>(inner.data());
-		setInnerTopSkip(topSkip);
-		setInnerBottomSkip(bottomSkip);
-		setInner(std::move(inner));
-		return result;
+		return setInnerWidget(
+			std::move(inner),
+			st::boxScroll,
+			topSkip,
+			bottomSkip);
 	}
 
 	template <typename Widget>
@@ -265,7 +269,6 @@ protected:
 private:
 	void finishPrepare();
 	void finishScrollCreate();
-	void setInner(object_ptr<TWidget> inner);
 	void setInner(object_ptr<TWidget> inner, const style::ScrollArea &st);
 	void updateScrollAreaGeometry();
 	void updateInnerVisibleTopBottom();

ui/layers/generic_box.cpp

@@ -29,10 +29,16 @@ void GenericBox::prepare() {
 		wrap->heightValue()
 	) | rpl::start_with_next([=](int top, int height) {
 		setInnerTopSkip(top);
-		setDimensions(currentWidth, top + height);
+		const auto desired = top + height;
+		setDimensions(
+			currentWidth,
+			_maxHeight ? std::min(desired, _maxHeight) : desired);
 	}, wrap->lifetime());
 
-	setInnerWidget(std::move(wrap), pinned ? pinned->height() : 0);
+	setInnerWidget(
+		std::move(wrap),
+		_scrollSt ? *_scrollSt : st::boxScroll,
+		pinned ? pinned->height() : 0);
 }
 
 void GenericBox::addSkip(int height) {

ui/layers/generic_box.h

@@ -71,6 +71,13 @@ public:
 
 	void addSkip(int height);
 
+	void setMaxHeight(int maxHeight) {
+		_maxHeight = maxHeight;
+	}
+	void setScrollStyle(const style::ScrollArea &st) {
+		_scrollSt = &st;
+	}
+
 	void setInnerFocus() override {
 		if (_focus) {
 			_focus();
@@ -128,7 +135,9 @@ private:
 	Fn<void()> _showFinished;
 	object_ptr<Ui::VerticalLayout> _owned;
 	not_null<Ui::VerticalLayout*> _content;
+	const style::ScrollArea *_scrollSt = nullptr;
 	int _width = 0;
+	int _maxHeight = 0;
 
 	object_ptr<Ui::RpWidget> _pinnedToTopContent = { nullptr };