riched20: Add get_total_width() to get widest paragraph number.

dlls/riched20/editor.h

@@ -202,6 +202,7 @@ void ME_MarkAllForWrapping(ME_TextEditor *editor) DECLSPEC_HIDDEN;
 void ME_SetDefaultParaFormat(ME_TextEditor *editor, PARAFORMAT2 *pFmt) DECLSPEC_HIDDEN;
 void para_num_init( ME_Context *c, ME_Paragraph *para ) DECLSPEC_HIDDEN;
 void para_num_clear( struct para_num *pn ) DECLSPEC_HIDDEN;
+int get_total_width(ME_TextEditor *editor) DECLSPEC_HIDDEN;
 
 /* paint.c */
 void ME_PaintContent(ME_TextEditor *editor, HDC hDC, const RECT *rcUpdate) DECLSPEC_HIDDEN;

dlls/riched20/para.c

@@ -36,11 +36,34 @@ void destroy_para(ME_TextEditor *editor, ME_DisplayItem *item)
 {
     assert(item->type == diParagraph);
 
+    if (item->member.para.nWidth == editor->nTotalWidth)
+    {
+        item->member.para.nWidth = 0;
+        editor->nTotalWidth = get_total_width(editor);
+    }
     ME_DestroyString(item->member.para.text);
     para_num_clear( &item->member.para.para_num );
     ME_DestroyDisplayItem(item);
 }
 
+int get_total_width(ME_TextEditor *editor)
+{
+    ME_Paragraph *para;
+    int total_width = 0;
+
+    if (editor->pBuffer->pFirst && editor->pBuffer->pLast)
+    {
+        para = &editor->pBuffer->pFirst->next->member.para;
+        while (para != &editor->pBuffer->pLast->member.para && para->next_para)
+        {
+            total_width = max(total_width, para->nWidth);
+            para = &para->next_para->member.para;
+        }
+    }
+
+    return total_width;
+}
+
 void ME_MakeFirstParagraph(ME_TextEditor *editor)
 {
   ME_Context c;