+At the heart of both clipboard and drag and drop operations lies the +wxDataObject class. The objects of this class (or, to be precise, +classes derived from it) represent the data which is being carried by +the mouse during drag and drop operation or copied to or pasted from +the clipboard. wxDataObject is a "smart" piece of data because it +knows which formats it supports (see GetFormatCount and GetAllFormats) +and knows how to render itself in any of them (see GetDataHere). It +can also receive its value from the outside in a format it supports if +it implements the SetData method. Please see the documentation of this +class for more details. +
+Both clipboard and drag and drop operations have two sides: the source +and target, the data provider and the data receiver. These which may +be in the same application and even the same window when, for example, +you drag some text from one position to another in a word +processor. Let us describe what each of them should do. + """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/FancyText.py b/wxPython/demo/FancyText.py index f504ccc21c..959a0dd1b5 100644 --- a/wxPython/demo/FancyText.py +++ b/wxPython/demo/FancyText.py @@ -38,3 +38,11 @@ def runTest(frame, nb, log): overview = fancytext.__doc__.replace("<", "<") + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/FileBrowseButton.py b/wxPython/demo/FileBrowseButton.py index 9967ea355f..798f201259 100644 --- a/wxPython/demo/FileBrowseButton.py +++ b/wxPython/demo/FileBrowseButton.py @@ -74,3 +74,12 @@ overview = """
""" % ( FileBrowseButton.__doc__, FileBrowseButtonWithHistory.__doc__ , str(DirBrowseButton.__doc__) ) + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/ImageBrowser.py b/wxPython/demo/ImageBrowser.py index 4e234695e0..4a38b95d7c 100644 --- a/wxPython/demo/ImageBrowser.py +++ b/wxPython/demo/ImageBrowser.py @@ -4,7 +4,7 @@ # # Author: Lorne White (email: lorne.white@telusplanet.net) # -# Version 0.5 +# Version 0.5 # Date: Feb 26, 2001 # Licence: wxWindows license #---------------------------------------------------------------------------- @@ -20,11 +20,11 @@ def runTest(frame, nb, log): initial_dir = os.path.join(dir, 'bitmaps') # set the initial directory for the demo bitmaps win = ImageDialog(frame, initial_dir) # open the image browser dialog win.Centre() - if win.ShowModal() == wxID_OK: + if win.ShowModal() == wxID_OK: log.WriteText("You Selected File: " + win.GetFile()) # show the selected file else: log.WriteText("You pressed Cancel\n") - + #--------------------------------------------------------------------------- @@ -38,3 +38,12 @@ def runTest(frame, nb, log): overview = """\ """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/LayoutAnchors.py b/wxPython/demo/LayoutAnchors.py index 04b0c3f92c..f4aa323ed6 100644 --- a/wxPython/demo/LayoutAnchors.py +++ b/wxPython/demo/LayoutAnchors.py @@ -136,5 +136,8 @@ overview = """ - +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/Layoutf.py b/wxPython/demo/Layoutf.py index cde4ad405f..b92faffeda 100644 --- a/wxPython/demo/Layoutf.py +++ b/wxPython/demo/Layoutf.py @@ -60,3 +60,12 @@ def runTest(frame, nb, log): overview = Layoutf.__doc__ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/OOR.py b/wxPython/demo/OOR.py index e0e84b0112..d58bc42bbd 100644 --- a/wxPython/demo/OOR.py +++ b/wxPython/demo/OOR.py @@ -136,3 +136,12 @@ and the second will show #2 (working as of 2.3.2) """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/PrintFramework.py b/wxPython/demo/PrintFramework.py index 36c3ea5a2b..664735473f 100644 --- a/wxPython/demo/PrintFramework.py +++ b/wxPython/demo/PrintFramework.py @@ -176,3 +176,12 @@ def runTest(frame, nb, log): overview = """\ """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/PythonEvents.py b/wxPython/demo/PythonEvents.py index d7454aac6b..98301706ff 100644 --- a/wxPython/demo/PythonEvents.py +++ b/wxPython/demo/PythonEvents.py @@ -83,3 +83,10 @@ This demo is a contrived example of defining an event class in wxPython and send + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/TablePrint.py b/wxPython/demo/TablePrint.py index 51b075c3da..7b370709d9 100644 --- a/wxPython/demo/TablePrint.py +++ b/wxPython/demo/TablePrint.py @@ -205,3 +205,12 @@ when the framework allows for it. """ % os.path.join(os.path.dirname(wxPython.lib.printout.__file__), "printout.py") + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/Threads.py b/wxPython/demo/Threads.py index 4c165eeb89..05883731b9 100644 --- a/wxPython/demo/Threads.py +++ b/wxPython/demo/Threads.py @@ -244,3 +244,11 @@ ProcessEvent does, it processes it later from the context of the GUI thread. """ + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/URLDragAndDrop.py b/wxPython/demo/URLDragAndDrop.py index 16b3b96006..51c1a340ad 100644 --- a/wxPython/demo/URLDragAndDrop.py +++ b/wxPython/demo/URLDragAndDrop.py @@ -121,3 +121,12 @@ def runTest(frame, nb, log): overview = """\ """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/Unicode.py b/wxPython/demo/Unicode.py index c6910a05c4..ec8a052bf9 100644 --- a/wxPython/demo/Unicode.py +++ b/wxPython/demo/Unicode.py @@ -139,3 +139,12 @@ and then pass the unicode to the wxPython method. """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/XMLtreeview.py b/wxPython/demo/XMLtreeview.py index d57642958e..081ac5f0f6 100644 --- a/wxPython/demo/XMLtreeview.py +++ b/wxPython/demo/XMLtreeview.py @@ -110,3 +110,11 @@ else: overview = """\ """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxCalendarCtrl.py b/wxPython/demo/wxCalendarCtrl.py index 7afc4c37d7..787ab71ae0 100644 --- a/wxPython/demo/wxCalendarCtrl.py +++ b/wxPython/demo/wxCalendarCtrl.py @@ -11,7 +11,10 @@ class TestPanel(wxPanel): self.log = log cal = wxCalendarCtrl(self, -1, wxDateTime_Now(), pos = (25,50), - style = wxCAL_SHOW_HOLIDAYS | wxCAL_SUNDAY_FIRST) + style = wxCAL_SHOW_HOLIDAYS + | wxCAL_SUNDAY_FIRST + #| wxCAL_SEQUENTIAL_MONTH_SELECTION + ) EVT_CALENDAR(self, cal.GetId(), self.OnCalSelected) @@ -55,3 +58,12 @@ version described in the docs. This one will probably be a bit more efficient than the one in wxPython.lib.calendar, but I like a few things about it better, so I think both will stay in wxPython. """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxCheckBox.py b/wxPython/demo/wxCheckBox.py index 46870444b0..529de660bb 100644 --- a/wxPython/demo/wxCheckBox.py +++ b/wxPython/demo/wxCheckBox.py @@ -51,3 +51,11 @@ overview = """\ A checkbox is a labelled box which is either on (checkmark is visible) or off (no checkmark). """ + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxCheckListBox.py b/wxPython/demo/wxCheckListBox.py index 434ecf2e06..8eec482923 100644 --- a/wxPython/demo/wxCheckListBox.py +++ b/wxPython/demo/wxCheckListBox.py @@ -70,13 +70,15 @@ def runTest(frame, nb, log): - - - - - - overview = """\ """ + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxChoice.py b/wxPython/demo/wxChoice.py index 9cd83ce3b2..d92f4f8e45 100644 --- a/wxPython/demo/wxChoice.py +++ b/wxPython/demo/wxChoice.py @@ -46,3 +46,13 @@ def runTest(frame, nb, log): overview = """\ A choice item is used to select one of a list of strings. Unlike a listbox, only the selection is visible until the user pulls down the menu of choices. """ + + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxColourDialog.py b/wxPython/demo/wxColourDialog.py index c4d42aebbf..151db30873 100644 --- a/wxPython/demo/wxColourDialog.py +++ b/wxPython/demo/wxColourDialog.py @@ -29,3 +29,13 @@ This class represents the colour chooser dialog. """ + + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxEditableListBox.py b/wxPython/demo/wxEditableListBox.py index b8816cad1d..97b951a6e0 100644 --- a/wxPython/demo/wxEditableListBox.py +++ b/wxPython/demo/wxEditableListBox.py @@ -40,3 +40,12 @@ overview = """\ This class provides a composite control that lets the user easily enter and edit a list of strings. """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxFileDialog.py b/wxPython/demo/wxFileDialog.py index a73dc06970..22856eb172 100644 --- a/wxPython/demo/wxFileDialog.py +++ b/wxPython/demo/wxFileDialog.py @@ -35,3 +35,12 @@ overview = """\ This class represents the file chooser dialog. """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxFindReplaceDialog.py b/wxPython/demo/wxFindReplaceDialog.py index c0217aedec..306c825205 100644 --- a/wxPython/demo/wxFindReplaceDialog.py +++ b/wxPython/demo/wxFindReplaceDialog.py @@ -76,3 +76,12 @@ def runTest(frame, nb, log): overview = """\ A generic find and replace dialog. """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxFloatBar.py b/wxPython/demo/wxFloatBar.py index ff323abe7e..1daf702276 100644 --- a/wxPython/demo/wxFloatBar.py +++ b/wxPython/demo/wxFloatBar.py @@ -75,9 +75,11 @@ def runTest(frame, nb, log): #--------------------------------------------------------------------------- overview = """\ -wxFloatBar is a subclass of wxToolBar, implemented in Python, which can be detached from its frame. +wxFloatBar is a subclass of wxToolBar, implemented in Python, which +can be detached from its frame. -Drag the toolbar with the mouse to make it float, and drag it back, or close it to make the toolbar return to its original position. +Drag the toolbar with the mouse to make it float, and drag it back, or +close it to make the toolbar return to its original position. """ @@ -87,6 +89,13 @@ Drag the toolbar with the mouse to make it float, and drag it back, or close it +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + + + diff --git a/wxPython/demo/wxFrame.py b/wxPython/demo/wxFrame.py index 428859beec..6fbc2d013f 100644 --- a/wxPython/demo/wxFrame.py +++ b/wxPython/demo/wxFrame.py @@ -43,3 +43,12 @@ def runTest(frame, nb, log): overview = """\ """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxGauge.py b/wxPython/demo/wxGauge.py index 21e185a439..754e1b4b21 100644 --- a/wxPython/demo/wxGauge.py +++ b/wxPython/demo/wxGauge.py @@ -52,3 +52,12 @@ def runTest(frame, nb, log): overview = """\ """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxGenericDirCtrl.py b/wxPython/demo/wxGenericDirCtrl.py index 7f338e67df..3af690277a 100644 --- a/wxPython/demo/wxGenericDirCtrl.py +++ b/wxPython/demo/wxGenericDirCtrl.py @@ -57,3 +57,10 @@ overview = """\ This control can be used to place a directory listing (with optional files) on an arbitrary window. """ + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxImageFromStream.py b/wxPython/demo/wxImageFromStream.py index 6953a2ca4c..1bf4fc7645 100644 --- a/wxPython/demo/wxImageFromStream.py +++ b/wxPython/demo/wxImageFromStream.py @@ -35,3 +35,12 @@ overview = """\ At long last there is finally a way to load any supported image type directly from any Python file-like object, such as a memory buffer using StringIO. """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxJoystick.py b/wxPython/demo/wxJoystick.py index 1c4882f40e..69555ee225 100644 --- a/wxPython/demo/wxJoystick.py +++ b/wxPython/demo/wxJoystick.py @@ -195,3 +195,12 @@ def runTest(frame, nb, log): overview = """\ """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxLEDNumberCtrl.py b/wxPython/demo/wxLEDNumberCtrl.py index d8907a35c1..4aead17541 100644 --- a/wxPython/demo/wxLEDNumberCtrl.py +++ b/wxPython/demo/wxLEDNumberCtrl.py @@ -46,3 +46,11 @@ def runTest(frame, nb, log): overview = """\ """ + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxLayoutConstraints.py b/wxPython/demo/wxLayoutConstraints.py index 4ffa033924..1c65b303df 100644 --- a/wxPython/demo/wxLayoutConstraints.py +++ b/wxPython/demo/wxLayoutConstraints.py @@ -114,10 +114,13 @@ def runTest(frame, nb, log): -overview = """\ -Objects of this class can be associated with a window to define its layout constraints, with respect to siblings or its parent. +overview = """\ +Objects of this class can be associated with a window to define its +layout constraints, with respect to siblings or its parent. -The class consists of the following eight constraints of class wxIndividualLayoutConstraint, some or all of which should be accessed directly to set the appropriate constraints. +The class consists of the following eight constraints of class +wxIndividualLayoutConstraint, some or all of which should be accessed +directly to set the appropriate constraints. left: represents the left hand edge of the window @@ -135,10 +138,21 @@ centreX: represents the horizontal centre point of the window centreY: represents the vertical centre point of the window -Most constraints are initially set to have the relationship wxUnconstrained, which means that their values should be calculated by looking at known constraints. The exceptions are width and height, which are set to wxAsIs to ensure that if the user does not specify a constraint, the existing width and height will be used, to be compatible with panel items which often have take a default size. If the constraint is wxAsIs, the dimension will not be changed. +Most constraints are initially set to have the relationship +wxUnconstrained, which means that their values should be calculated by +looking at known constraints. The exceptions are width and height, +which are set to wxAsIs to ensure that if the user does not specify a +constraint, the existing width and height will be used, to be +compatible with panel items which often have take a default size. If +the constraint is wxAsIs, the dimension will not be changed. -wxLayoutConstraints() -------------------------------------------- - -Constructor. """ + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) + diff --git a/wxPython/demo/wxMDIWindows.py b/wxPython/demo/wxMDIWindows.py index 7eef8a39c9..9df21dc221 100644 --- a/wxPython/demo/wxMDIWindows.py +++ b/wxPython/demo/wxMDIWindows.py @@ -52,3 +52,12 @@ it. Here are a couple samples of how to use it. """ + + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxMVCTree.py b/wxPython/demo/wxMVCTree.py index 808f8870b3..17d71cd211 100644 --- a/wxPython/demo/wxMVCTree.py +++ b/wxPython/demo/wxMVCTree.py @@ -51,13 +51,22 @@ def runTest(frame, nb, log): overview = """\ -wxMVCTree is a control which handles hierarchical data. It is constructed in model-view-controller architecture, so the display of that data, and the content of the data can be changed greatly without affecting the other parts. + +wxMVCTree is a control which handles hierarchical data. It is +constructed in model-view-controller architecture, so the display of +that data, and the content of the data can be changed greatly without +affecting the other parts. Multiple selections are possible by holding down the Ctrl key. -This demo shows the wxPython directory structure. The interesting part is that the tree model is late-bound to the filesystem, so the filenames are not retrieved until the directory is expanded. In mvctree.py are models for generic data, and both the early and late-bound filesystem models. +This demo shows the wxPython directory structure. The interesting part +is that the tree model is late-bound to the filesystem, so the +filenames are not retrieved until the directory is expanded. In +mvctree.py are models for generic data, and both the early and +late-bound filesystem models. -There is also support for editing, though it's not enabled in this demo, to avoid accidentally renaming files! +There is also support for editing, though it's not enabled in this +demo, to avoid accidentally renaming files! """ @@ -65,6 +74,7 @@ There is also support for editing, though it's not enabled in this demo, to avoi - - - +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxMessageDialog.py b/wxPython/demo/wxMessageDialog.py index 17dcf7d741..b75d907739 100644 --- a/wxPython/demo/wxMessageDialog.py +++ b/wxPython/demo/wxMessageDialog.py @@ -25,39 +25,14 @@ def runTest(frame, nb, log): overview = """\ -wxMessageDialog() ----------------------------------- - -wxMessageDialog(wxWindow* parent, const wxString& message, const wxString& caption = "Message box", long style = wxOK | wxCANCEL | wxCENTRE, const wxPoint& pos = wxDefaultPosition) - -Constructor. Use wxMessageDialog::ShowModal to show the dialog. - -Parameters -------------------- - -parent = Parent window. - -message = Message to show on the dialog. - -caption = The dialog caption. - -style = A dialog style (bitlist) containing flags chosen from the following: - -wxOK Show an OK button. - -wxCANCEL Show a Cancel button. - -wxYES_NO Show Yes and No buttons. - -wxCENTRE Centre the message. Not Windows. - -wxICON_EXCLAMATION Shows an exclamation mark icon. Windows only. - -wxICON_HAND Shows a hand icon. Windows only. - -wxICON_QUESTION Shows a question mark icon. Windows only. - -wxICON_INFORMATION Shows an information (i) icon. Windows only. - -pos = Dialog position. +Show a message to the user in a dialog """ + + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxMimeTypesManager.py b/wxPython/demo/wxMimeTypesManager.py index 39ba2074dc..d6356389d4 100644 --- a/wxPython/demo/wxMimeTypesManager.py +++ b/wxPython/demo/wxMimeTypesManager.py @@ -173,3 +173,11 @@ def MyBitmapsFunc( index ): mimetypes_wdr.MyBitmapsFunc = MyBitmapsFunc + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxMiniFrame.py b/wxPython/demo/wxMiniFrame.py index fd7c6c7f45..b92e300eda 100644 --- a/wxPython/demo/wxMiniFrame.py +++ b/wxPython/demo/wxMiniFrame.py @@ -45,3 +45,12 @@ def runTest(frame, nb, log): overview = """\ """ + + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxMultipleChoiceDialog.py b/wxPython/demo/wxMultipleChoiceDialog.py index 6e3fb5de55..c7f93764e1 100644 --- a/wxPython/demo/wxMultipleChoiceDialog.py +++ b/wxPython/demo/wxMultipleChoiceDialog.py @@ -25,3 +25,12 @@ def runTest(frame, nb, log): overview = """\ """ + + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxPageSetupDialog.py b/wxPython/demo/wxPageSetupDialog.py index 61ae29290d..df344ec6ab 100644 --- a/wxPython/demo/wxPageSetupDialog.py +++ b/wxPython/demo/wxPageSetupDialog.py @@ -21,13 +21,15 @@ def runTest(frame, nb, log): - - - - - - - - overview = """\ """ + + + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxPlotCanvas.py b/wxPython/demo/wxPlotCanvas.py index 1a9f7b2271..5f1a42ed91 100644 --- a/wxPython/demo/wxPlotCanvas.py +++ b/wxPython/demo/wxPlotCanvas.py @@ -37,3 +37,11 @@ def runTest(frame, nb, log): overview = wxPlotCanvas.__doc__ #--------------------------------------------------------------------------- + + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxPrintDialog.py b/wxPython/demo/wxPrintDialog.py index 183cbe801c..2de009cc54 100644 --- a/wxPython/demo/wxPrintDialog.py +++ b/wxPython/demo/wxPrintDialog.py @@ -18,14 +18,12 @@ def runTest(frame, nb, log): - - - - - - - - - overview = """\ """ + + + +if __name__ == '__main__': + import sys,os + import run + run.main(['', os.path.basename(sys.argv[0])]) diff --git a/wxPython/demo/wxProcess.py b/wxPython/demo/wxProcess.py index d8104e5e75..b9bd6ceb66 100644 --- a/wxPython/demo/wxProcess.py +++ b/wxPython/demo/wxProcess.py @@ -152,3 +152,12 @@ child process to exit its main loop.