Please see attached recording. Steps:

• Create a new project
• Add new model
• Add new columns to new model so that not all fit in Model Editor view and you can scroll the view by dragging with mouse (or use the default book model)
• Make some of the columns wider
• Grab the table with mouse and move to right and left
• -> At some point headers break so that they are not the same width as the column
• -> Add column button disappears from right side of the table
• Resizing the view seems to recover header width
• Adding a new row might bring the "add column" button back