Wide char fixes

XtermSharp/Terminal.cs

@@ -964,8 +964,16 @@ namespace XtermSharp {
 			int left = MarginMode ? buffer.MarginLeft : 0;
 			int right = MarginMode ? buffer.MarginRight : buffer.Cols - 1;
 
-			if (buffer.X > left) {
-				buffer.X--;
+			var x = buffer.X;
+			var bufferLine = buffer.Lines[buffer.Y + buffer.YBase];
+			var width = 1;
+            while (x > 0 && bufferLine[x].IsNullChar()) {
+				x--;
+            }
+
+			width = bufferLine[x].Width;
+            if (buffer.X > left) {
+                buffer.X -= width;
 			} else if (ReverseWraparound) {
 				if (buffer.X <= left) {
 					if (buffer.Y > buffer.ScrollTop && buffer.Y <= buffer.ScrollBottom && (buffer.Lines [buffer.Y + buffer.YBase].IsWrapped || MarginMode)) {
@@ -989,11 +997,12 @@ namespace XtermSharp {
 					// This compensates for the scenario where backspace is supposed to move one step
 					// backwards if the "x" position is behind the left margin.
 					// Test BS_MovesLeftWhenLeftOfLeftMargin
-					buffer.X--;
-				} else if (buffer.X > left) {
-					// If we have not reached the limit, we can go back, otherwise stop at the margin
-					// Test BS_StopsAtLeftMargin
-					buffer.X--;
+                    buffer.X -= width;
+                }
+                else if (buffer.X > left) {
+                    // If we have not reached the limit, we can go back, otherwise stop at the margin
+                    // Test BS_StopsAtLeftMargin
+                    buffer.X -= width;
 
 				}
 			}