From 78808418888af2ecab9da4b36db95c32b95fb13d Mon Sep 17 00:00:00 2001
From: Bo Peng <bpeng@lyx.org>
Date: Sun, 19 Nov 2006 18:33:13 +0000
Subject: [PATCH] BUG 686: delete empty math box with delete/backspace key 
 * src/cursor.C: remove nested empty math box 	* src/mathed/InsetMathNest.C:
 remove the whole empty math box if it 	  can not be deleted from within

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@15990 a592a061-630c-0410-9148-cb99ea01b6c8
---
 src/cursor.C               | 33 ++++++++++++++++++++++++++-------
 src/mathed/InsetMathNest.C | 12 ++++++++++--
 2 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/src/cursor.C b/src/cursor.C
index 42a0c7cf1b..24befe6a99 100644
--- a/src/cursor.C
+++ b/src/cursor.C
@@ -747,10 +747,22 @@ bool LCursor::backspace()
 	}
 
 	if (pos() == 0) {
-		if (inset().nargs() == 1 && depth() == 1 && lastpos() == 0)
+		// If empty cell, and not part of a big cell
+		if (lastpos() == 0 && inset().nargs() == 1) {
+			popLeft();
+			// Directly delete empty cell: [|[]] => [|] 
+			if (inMathed()) {
+				plainErase();
+				resetAnchor();
+				return true;
+			}
+			// [|], can not delete from inside
 			return false;
-		pullArg();
-		return true;
+		} else {
+			// move to left
+			popLeft();
+			return true;
+		}
 	}
 
 	if (inMacroMode()) {
@@ -793,12 +805,19 @@ bool LCursor::erase()
 	// special behaviour when in last position of cell
 	if (pos() == lastpos()) {
 		bool one_cell = inset().nargs() == 1;
-		if (one_cell && depth() == 1 && lastpos() == 0)
+		if (one_cell && lastpos() == 0) {
+			popLeft();
+			// Directly delete empty cell: [|[]] => [|] 
+			if (inMathed()) {
+				plainErase();
+				resetAnchor();
+				return true;
+			}
+			// [|], can not delete from inside
 			return false;
+		}
 		// remove markup
-		if (one_cell)
-			pullArg();
-		else
+		if (!one_cell)
 			inset().idxGlue(idx());
 		return true;
 	}
diff --git a/src/mathed/InsetMathNest.C b/src/mathed/InsetMathNest.C
index 2f2d312e3e..49867f7fe3 100644
--- a/src/mathed/InsetMathNest.C
+++ b/src/mathed/InsetMathNest.C
@@ -648,7 +648,11 @@ void InsetMathNest::doDispatch(LCursor & cur, FuncRequest & cmd)
 			recordUndoInset(cur, Undo::ATOMIC);
 		else
 			recordUndo(cur, Undo::ATOMIC);
-		cur.backspace();
+		// if the inset can not be removed from within, delete it
+		if (!cur.backspace()) {
+			FuncRequest cmd = FuncRequest(LFUN_CHAR_DELETE_FORWARD);
+			cur.bv().getLyXText()->dispatch(cur, cmd);
+		}
 		break;
 
 	case LFUN_WORD_DELETE_FORWARD:
@@ -658,7 +662,11 @@ void InsetMathNest::doDispatch(LCursor & cur, FuncRequest & cmd)
 			recordUndoInset(cur, Undo::ATOMIC);
 		else
 			recordUndo(cur, Undo::ATOMIC);
-		cur.erase();
+		// if the inset can not be removed from within, delete it
+		if (!cur.erase()) {
+			FuncRequest cmd = FuncRequest(LFUN_CHAR_DELETE_FORWARD);
+			cur.bv().getLyXText()->dispatch(cur, cmd);
+		}
 		break;
 
 	case LFUN_ESCAPE: