[LyX/master] When breaking a paragraph, do not reset depth

[Jean-Marc Lasgouttes]

commit 13d24c711e745ea0c6ea2019236025d14bd2defa
Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
Date:   Sun Mar 26 20:28:00 2023 +0200

    When breaking a paragraph, do not reset depth
    
    Remove some logic that would reset depth when editing non-environment
    stuff (e.g. Standard layout) at non-zero depth. The current way of
    decreasing depth is to use paragraph-break in an empty paragraph.
    
    See discussion in ticket #2445 for why this code happened.
    
    Fixes bug #12750.
---
 src/Text.cpp |   19 +++++--------------
 1 files changed, 5 insertions(+), 14 deletions(-)

diff --git a/src/Text.cpp b/src/Text.cpp
index a61e325..dfef748 100644
--- a/src/Text.cpp
+++ b/src/Text.cpp
@@ -716,9 +716,8 @@ double Text::spacing(Paragraph const & par) const
 /**
  * This breaks a paragraph at the specified position.
  * The new paragraph will:
- * - Decrease depth by one (or change layout to default layout) when
- *    keep_layout == false
- * - keep current depth and layout when keep_layout == true
+ * - change layout to default layout when keep_layout == false
+ * - keep layout when keep_layout == true
  */
 static void breakParagraph(Text & text, pit_type par_offset, pos_type pos,
 		    bool keep_layout)
@@ -733,21 +732,13 @@ static void breakParagraph(Text & text, pit_type par_offset, pos_type pos,
 
 	// remember to set the inset_owner
 	tmp->setInsetOwner(&par.inInset());
-	// without doing that we get a crash when typing <Return> at the
-	// end of a paragraph
-	tmp->setPlainOrDefaultLayout(bparams.documentClass());
+	tmp->params().depth(par.params().depth());
 
 	if (keep_layout) {
 		tmp->setLayout(par.layout());
 		tmp->setLabelWidthString(par.params().labelWidthString());
-		tmp->params().depth(par.params().depth());
-	} else if (par.params().depth() > 0) {
-		Paragraph const & hook = pars[text.outerHook(par_offset)];
-		tmp->setLayout(hook.layout());
-		// not sure the line below is useful
-		tmp->setLabelWidthString(par.params().labelWidthString());
-		tmp->params().depth(hook.params().depth());
-	}
+	} else
+		tmp->setPlainOrDefaultLayout(bparams.documentClass());
 
 	bool const isempty = (par.allowEmpty() && par.empty());