Add browser_did_fetch_columns hook and some doc

qt/aqt/table.py

@@ -817,16 +817,27 @@ def backend_color_to_aqt_color(color: BrowserRow.Color.V) -> Optional[Tuple[str,
 
 
 class DataModel(QAbstractTableModel):
+    """Data manager for the browser table.
+
+    _items -- The card or note ids currently hold and corresponding to the
+              table's rows.
+    _rows -- The cached data objects to render items to rows.
+    columns -- The data objects of all available columns, used to define the display
+               of active columns and list all toggleable columns to the user.
+    _block_updates -- If True, serve stale content to avoid hitting the DB.
+    _stale_cutoff -- A threshold to decide whether a cached row has gone stale.
+    """
+
     def __init__(self, col: Collection, state: ItemState) -> None:
         QAbstractTableModel.__init__(self)
         self.col: Collection = col
         self.columns: Dict[str, Column] = dict(
             ((c.key, c) for c in self.col.all_browser_columns())
         )
+        gui_hooks.browser_did_fetch_columns(self.columns)
         self._state: ItemState = state
         self._items: Sequence[ItemId] = []
         self._rows: Dict[int, CellRow] = {}
-        # serve stale content to avoid hitting the DB?
         self._block_updates = False
         self._stale_cutoff = 0.0
 

qt/tools/genhooks_gui.py

@@ -16,7 +16,7 @@ prefix = """\
 
 from __future__ import annotations
 
-from typing import Any, Callable, List, Sequence, Tuple, Optional, Union
+from typing import Any, Callable, Dict, List, Sequence, Tuple, Optional, Union
 
 import anki
 import aqt
@@ -423,6 +423,18 @@ hooks = [
         represents.
         """,
     ),
+    Hook(
+        name="browser_did_fetch_columns",
+        args=["columns: Dict[str, aqt.table.Column]"],
+        doc="""Allows you to add custom columns to the browser.
+        
+        columns is a dictionary of data obejcts. You can add an entry with a custom
+        column to describe how it should be displayed in the browser or modify
+        existing entries.
+
+        Every column in the dictionary will be toggleable by the user.
+        """,
+    ),
     # Main window states
     ###################
     # these refer to things like deckbrowser, overview and reviewer state,