1) Failed to fetch query history error sometimes.
2) In copy paste row, if a copied row has [null], then those are pasted as an empty string.
3) When Data output is empty, show an empty grid.
4) Schema diff generates a script button resulting in an empty window. Fixes#7306.
5) Detach the DataOutput panel > Try editing text cell > Text editor is hidden behind the data output panel
refs #6131