[LyX/master] Remove some spacing above InsetColapsible when possible

[Jean-Marc Lasgouttes]

commit eeb4187a281b9a5b4bfe8a0576f80f28334b3c90
Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
Date:   Wed Jan 15 11:12:47 2020 +0100

    Remove some spacing above InsetColapsible when possible
---
 src/insets/InsetCollapsible.cpp |   25 +++++++++++++++++++++----
 src/insets/InsetCollapsible.h   |    6 ++++++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/insets/InsetCollapsible.cpp b/src/insets/InsetCollapsible.cpp
index f0b32c8..09e5f3d 100644
--- a/src/insets/InsetCollapsible.cpp
+++ b/src/insets/InsetCollapsible.cpp
@@ -157,6 +157,27 @@ void InsetCollapsible::read(Lexer & lex)
 	setButtonLabel();
 }
 
+int InsetCollapsible::topOffset(BufferView const * bv) const
+{
+	switch (geometry(*bv)) {
+	case Corners:
+	case SubLabel:
+		return 0;
+	default:
+		return InsetText::topOffset(bv);
+	}
+}
+
+int InsetCollapsible::bottomOffset(BufferView const * bv) const
+{
+	switch (geometry(*bv)) {
+	case Corners:
+		return InsetText::topOffset(bv) / 4;
+	default:
+		return InsetText::topOffset(bv);
+	}
+}
+
 
 Dimension InsetCollapsible::dimensionCollapsed(BufferView const & bv) const
 {
@@ -185,8 +206,6 @@ void InsetCollapsible::metrics(MetricsInfo & mi, Dimension & dim) const
 		break;
 	case Corners:
 		InsetText::metrics(mi, dim);
-		dim.des -= 3;
-		dim.asc -= 1;
 		break;
 	case SubLabel: {
 		InsetText::metrics(mi, dim);
@@ -319,8 +338,6 @@ void InsetCollapsible::draw(PainterInfo & pi, int x, int y) const
 		}
 
 		int desc = textdim.descent();
-		if (g == Corners)
-			desc -= 3;
 
 		// Colour the frame according to the change type. (Like for tables.)
 		Color colour = pi.change.changed() ? pi.change.color()
diff --git a/src/insets/InsetCollapsible.h b/src/insets/InsetCollapsible.h
index 423f234..95a8e1f 100644
--- a/src/insets/InsetCollapsible.h
+++ b/src/insets/InsetCollapsible.h
@@ -54,6 +54,12 @@ public:
 	void read(Lexer &);
 	///
 	void write(std::ostream &) const;
+
+	///
+	int topOffset(BufferView const * bv) const;
+	///
+	int bottomOffset(BufferView const * bv) const;
+
 	///
 	void metrics(MetricsInfo &, Dimension &) const;
 	///