Fix sizing of temporarily last columns in macOS wxDataViewCtrl

Update the column width if it used to be the last one but isn't last one
any longer.

Closes #14939.

include/wx/osx/cocoa/dataview.h

@@ -86,7 +86,7 @@ class wxCocoaDataViewControl;
 class wxDataViewColumnNativeData
 {
 public:
-    wxDataViewColumnNativeData() : m_NativeColumnPtr(NULL)
+    wxDataViewColumnNativeData() : m_NativeColumnPtr(NULL), m_isLast(false), m_prevWidth(0)
     {
     }
 
@@ -105,9 +105,32 @@ public:
         m_NativeColumnPtr = newNativeColumnPtr;
     }
 
+    bool GetIsLast() const
+    {
+        return m_isLast;
+    }
+
+    void SetIsLast(bool isLast)
+    {
+        m_isLast = isLast;
+    }
+
+    int GetPrevWidth() const
+    {
+        return m_prevWidth;
+    }
+
+    void SetPrevWidth(int prevWidth)
+    {
+        m_prevWidth = prevWidth;
+    }
+
 private:
     // not owned by us
     NSTableColumn* m_NativeColumnPtr;
+
+    bool m_isLast;
+    int m_prevWidth;
 };
 
 // ============================================================================

src/osx/cocoa/dataview.mm

@@ -2206,7 +2206,8 @@ bool wxCocoaDataViewControl::InsertColumn(unsigned int pos, wxDataViewColumn* co
 void wxCocoaDataViewControl::FitColumnWidthToContent(unsigned int pos)
 {
     const int count = GetCount();
-    NSTableColumn *column = GetColumn(pos)->GetNativeData()->GetNativeColumnPtr();
+    wxDataViewColumnNativeData *nativeData = GetColumn(pos)->GetNativeData();
+    NSTableColumn *column = nativeData->GetNativeColumnPtr();
     UInt32 const noOfColumns = [[m_OutlineView tableColumns] count];
 
     class MaxWidthCalculator
@@ -2338,10 +2339,31 @@ void wxCocoaDataViewControl::FitColumnWidthToContent(unsigned int pos)
     if ( m_expanderWidth == 0 )
         m_expanderWidth = calculator.GetExpanderWidth();
 
-    if ( pos == noOfColumns - 1 )
+    const bool isLast = pos == noOfColumns - 1;
+
+    if ( isLast )
+    {
+        // Note that FitColumnWidthToContent() is called whenever a column is
+        // added, so we might also just temporarily become the last column;
+        // since we cannot know at this time whether we will just temporarily
+        // be the last column, we store our current column width in order to
+        // restore it later in case we suddenly are no longer the last column
+        // because new columns have been added --> we need to restore our
+        // previous width in that case because it must not get lost.
+        nativeData->SetPrevWidth(GetColumn(pos)->GetWidth());
+
         [m_OutlineView sizeLastColumnToFit];
+    }
     else if ( GetColumn(pos)->GetWidthVariable() == wxCOL_WIDTH_AUTOSIZE )
+    {
         [column setWidth:calculator.GetMaxWidth() + m_expanderWidth];
+    }
+    else if ( nativeData->GetIsLast() )
+    {
+        [column setWidth:nativeData->GetPrevWidth()];
+    }
+
+    nativeData->SetIsLast(isLast);
 
     if ( !(GetDataViewCtrl()->GetWindowStyle() & wxDV_VARIABLE_LINE_HEIGHT) )
     {

src/osx/dataview_osx.cpp

@@ -438,6 +438,9 @@ bool wxDataViewCtrl::InsertColumn(unsigned int pos, wxDataViewColumn* columnPtr)
      // otherwise ask the control to 'update' the data in the newly appended column:
       if (GetColumnCount() == 1)
         SetExpanderColumn(columnPtr);
+
+      AdjustAutosizedColumns();
+
      // done:
       return true;
     }
@@ -479,6 +482,8 @@ bool wxDataViewCtrl::DeleteColumn(wxDataViewColumn* columnPtr)
   {
     m_ColumnPtrs.Remove(columnPtr);
     delete columnPtr;
+
+    AdjustAutosizedColumns();
     return true;
   }
   else