Merge branch 'spinctrl-fixes'

Various improvements to wxSpinCtrl and wxGridCellNumberEditor, using it.

Closes https://github.com/wxWidgets/wxWidgets/pull/1588

interface/wx/control.h

@@ -140,6 +140,27 @@ public:
     */
     wxSize GetSizeFromTextSize(const wxSize& tsize) const;
 
+    /**
+        Determine the minimum size needed by the control to display the given text.
+
+        The helper function that uses combination of GetSizeFromTextSize() and
+        GetTextExtent() which used together pretty often:
+        @code
+            wxSize GetSizeFromText(const wxString& text) const
+            {
+                return GetSizeFromTextSize(GetTextExtent(text).GetWidth());
+            }
+        @endcode
+
+        @param text The given text.
+        @return The size that the control should have to leave the area of the
+            specified text. May return wxDefaultSize if this method is not
+            implemented for this particular control under the current platform.
+
+        @since 3.1.3
+     */
+    wxSize GetSizeFromText(const wxString& text) const;
+
     /**
         Sets the control's label.