Avoid infinite loop

Fixes: #11295
(cherry picked from commit 92bfa07a6205e6e2aae486510c148582e11d6017)

src/LyXAction.cpp

@@ -1517,7 +1517,7 @@ void LyXAction::init()
  * \li Params: outer: If this is given, LyX will split the outermost environment in
                       the current nesting hierarchy.\n
                previous: If this is given, LyX will split the environment in the previous
-                      paragraph (is there is one).\n
+                         paragraph (if there is one).\n
                before:   If this is given, the new environment will be appended rather than
                          prepended.
  * \li Origin: spitz, 23 Dec 2012

src/Text3.cpp

@@ -1654,8 +1654,13 @@ void Text::dispatch(Cursor & cur, FuncRequest & cmd)
 			DocIterator scur = cur;
 			depth_type const max_depth = cur.paragraph().params().depth() + 1;
 			cur.forwardPar();
-			while (cur.paragraph().params().depth() < min(nextpar_depth, max_depth))
+			while (cur.paragraph().params().depth() < min(nextpar_depth, max_depth)) {
+				depth_type const olddepth = cur.paragraph().params().depth();
 				lyx::dispatch(FuncRequest(LFUN_DEPTH_INCREMENT));
+				if (olddepth == cur.paragraph().params().depth())
+					// leave loop if no incrementation happens
+					break;
+			}
 			cur.setCursor(scur);
 		}
 

status.23x

@@ -108,6 +108,8 @@ What's new
 
 * USER INTERFACE
 
+- Fix infinite loop while separating environments (bug 11295).
+
 - Fix loss of citation list after Undo (bug 9158).
 
 - Fix document-wide language setting with minted (bug 11203).
@@ -120,7 +122,7 @@ What's new
 
 - Draw menu separator symbol according to text direction.
 
-- Improve automatic removal of extra spaces, aka DEPM (bug 10503)
+- Improve automatic removal of extra spaces, aka DEPM (bug 10503).