Preserve size of wxGrid rows/columns when hiding and showing them back.

Previously, if a wxGrid row or column was hidden by setting its size to 0, its
original size was lost. Change this so that it's preserved now and can be
restored by setting the size to the special -1 value later.

Closes #14133.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72491 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/grid.h

@@ -2923,7 +2923,10 @@ public:
         Hides the specified column.
 
         To show the column later you need to call SetColSize() with non-0
-        width or ShowCol().
+        width or ShowCol() to restore the previous column width.
+
+        Notice that this method shouldn't be called if the column is already
+        hidden.
 
         @param col
             The column index.
@@ -2933,6 +2936,12 @@ public:
     /**
         Shows the previously hidden column by resizing it to non-0 size.
 
+        The column is shown again with the same width that it had before
+        HideCol() call.
+
+        Notice that this method shouldn't be called if the column is not
+        currently hidden.
+
         @see HideCol(), SetColSize()
      */
     void ShowCol(int col);
@@ -2994,7 +3003,7 @@ public:
         Hides the specified row.
 
         To show the row later you need to call SetRowSize() with non-0
-        width or ShowRow().
+        width or ShowRow() to restore its original height.
 
         @param col
             The row index.
@@ -3002,7 +3011,10 @@ public:
     void HideRow(int col);
 
     /**
-        Shows the previously hidden row by resizing it to non-0 size.
+        Shows the previously hidden row.
+
+        The row is shown again with the same height that it had before
+        HideRow() call.
 
         @see HideRow(), SetRowSize()
      */