Fixes for nested ulem commands

1. \uuline must be on top of \sout
2. \uwave in \xout needs a hack to compile

(cherry picked from commit 9fd94a2dd0)

src/Font.cpp

@@ -441,6 +441,11 @@ int Font::latexWriteStartChanges(odocstream & os, BufferParams const & bparams,
 		count += 10;
 		++runparams.inulemcmd;
 	}
+	if (f.uuline() == FONT_ON) {
+		os << "\\uuline{";
+		count += 11;
+		++runparams.inulemcmd;
+	}
 	if (f.strikeout() == FONT_ON) {
 		os << "\\sout{";
 		count += 9;
@@ -451,12 +456,13 @@ int Font::latexWriteStartChanges(odocstream & os, BufferParams const & bparams,
 		count += 9;
 		++runparams.inulemcmd;
 	}
-	if (f.uuline() == FONT_ON) {
-		os << "\\uuline{";
-		count += 11;
-		++runparams.inulemcmd;
-	}
 	if (f.uwave() == FONT_ON) {
+		if (runparams.inulemcmd) {
+			// needed with nested uwave in xout
+			// see https://tex.stackexchange.com/a/263042
+			os << "\\ULdepth=1000pt";
+			count += 15;
+		}
 		os << "\\uwave{";
 		count += 10;
 		++runparams.inulemcmd;

status.23x

@@ -143,6 +143,8 @@ What's new
 
 - Load hyperref with a suitable driver (bug 6418).
 
+- Fix LaTeX errors with nested ulem commands.
+
 - Recompile grandchildren when they have updated (bug 11112).
 
 - Output list of bibliography files in the order given in the dialog, rather