Spreadsheet: Add undo/redo implementation

The Spreadsheet application currently does not support undo/redo,
and with this update, we are starting the process of adding this feature
:-)

Additionally, the save dialog has been updated to use
GUI::MessageBox::ask_about_unsaved_changes() for system cohesity.

Spreadsheet: Add basic undo functinoality

The spreadsheet application now has basic support for undo. Testing of
this feature is limited, and may not work as intended yet.

Spreadsheet: Add callback when a cell's value is changed

In addition to the callback being added, this commit also exposes the
SheetModel class via a getter in SpreadSheetView.

Spreadsheet: Remove debug statements and use cell change callback

This commit uses the on_cell_data_change callback from within the
SheetModel class. This allows for us to push/pop changes to the undo
stack.

With this, we have basic Undo/Redo functionality :-)

Spreadsheet: Actually add window::set_modified

Spreadsheet: Const-correctness :-)

Spreadsheet: Reorder the edit menu actions

1 files changed, 3 insertions, 0 deletions

diff --git a/Userland/Applications/Spreadsheet/SpreadsheetModel.cpp b/Userland/Applications/Spreadsheet/SpreadsheetModel.cpp
index 51b1c5cca4..e7980430f0 100644
--- a/Userland/Applications/Spreadsheet/SpreadsheetModel.cpp
+++ b/Userland/Applications/Spreadsheet/SpreadsheetModel.cpp
@@ -153,7 +153,10 @@ void SheetModel::set_data(const GUI::ModelIndex& index, const GUI::Variant& valu
         return;
 
     auto& cell = m_sheet->ensure({ (size_t)index.column(), (size_t)index.row() });
+    auto previous_data = cell.data();
     cell.set_data(value.to_string());
+    if (on_cell_data_change)
+        on_cell_data_change(cell, previous_data);
     did_update(UpdateFlag::DontInvalidateIndices);
 }