[patch] bug 3590: ctrl-minus, ctrl-z crashes Lyx in maths editor

[Jürgen Spitzmüller]

The reason is simple: LyX inserts a hyphenation-inset, which is simply invalid 
in mathed (and hence drawn outside). This confuses undo.

Simple fix: disable the specialchar insets in mathed (see attached patch). 
Also a candidate for 1.4. (same crashes)

However, in math-text mode, lots of these lfuns would make sense, so they 
could be implemented later (for instance, \- or even \textcompwordmark in 
math-text seems to do the right thing; I've added a FIXME).

OK to apply?

Jürgen

Index: src/mathed/InsetMathNest.cpp
===================================================================
--- src/mathed/InsetMathNest.cpp	(Revision 18346)
+++ src/mathed/InsetMathNest.cpp	(Arbeitskopie)
@@ -1089,6 +1089,15 @@
 		flag.enabled(cur.selBegin().idx() == cur.selEnd().idx());
 		break;
 
+	case LFUN_HYPHENATION_POINT_INSERT:
+	case LFUN_LIGATURE_BREAK_INSERT:
+	case LFUN_MENU_SEPARATOR_INSERT:
+	case LFUN_DOTS_INSERT:
+	case LFUN_END_OF_SENTENCE_PERIOD_INSERT:
+		// FIXME: These would probably make sense in math-text mode
+		flag.enabled(false);
+		break;
+
 	default:
 		ret = false;
 		break;