add --no-display flag to %%capture

document this new magic in whatsnew, and added docs to the resulting object.

IPython/core/magics/execution.py

@@ -1166,13 +1166,17 b' python-profiler package from non-free.""")'
     @magic_arguments.argument('--no-stdout', action="store_true",
         help="""Don't capture stdout."""
     )
+    @magic_arguments.argument('--no-display', action="store_true",
+        help="""Don't capture IPython's rich display."""
+    )
     @cell_magic
     def capture(self, line, cell):
-        """run the cell, capturing stdout/err"""
+        """run the cell, capturing stdout, stderr, and IPython's rich display() calls."""
         args = magic_arguments.parse_argstring(self.capture, line)
         out = not args.no_stdout
         err = not args.no_stderr
-        with capture_output(out, err) as io:
+        disp = not args.no_display
+        with capture_output(out, err, disp) as io:
             self.shell.run_cell(cell)
         if args.output:
             self.shell.user_ns[args.output] = io

IPython/utils/capture.py

@@ -65,7 +65,17 b' class RichOutput(object):'
 
 
 class CapturedIO(object):
-    """Simple object for containing captured stdout/err StringIO objects"""
+    """Simple object for containing captured stdout/err and rich display StringIO objects
+
+    Each instance `c` has three attributes:
+
+        c.stdout : standard output as a string
+        c.stderr : standard error as a string
+        c.outputs: a list of rich display outputs
+
+    Additionally, there's a `c.show()` method which will print all of the
+    above in the same order, and can be invoked simply via `c()`.
+    """
     
     def __init__(self, stdout, stderr, outputs=None):
         self._stdout = stdout
@@ -130,7 +140,7 b' class capture_output(object):'
                 self.save_display_pub = None
                 self.display = False
         
-        stdout = stderr = outputs = False
+        stdout = stderr = outputs = None
         if self.stdout:
             stdout = sys.stdout = StringIO()
         if self.stderr:

docs/source/whatsnew/development.rst

@@ -4,6 +4,9 b''
 
 This document describes in-flight development work.
 
+- `%%capture` cell magic now captures the rich display output, not just
+  stdout/stderr
+
 
 Backwards incompatible changes
 ------------------------------