Avoiding QGIS plugin window to open at start

Question

I have written a few QGIS plugins based on dockwidget (Spectre Viewer and Stripchart viewer). When opened, the plugin window is expected to stay open and react to interactions with opened layers. This works fine, but an annoyance is that when the plugin is installed and active, its window will open as soon as I start QGIS. I do not want them to appear until I open the plugin from the menu or toolbar. How can I do this?

The problem seems to be the opposite of QGIS plugins open automatically when starting QGIS, but I cannot see how the answer to this could help me (I do not have any startup.py in my plugins)

Answer 1

I made the following edits to your plugin's qgisSpectre.py file in my local installation which seem to have fixed the problem. You can make the same changes in your local installation to test, then update your plugin.

Move the line which creates the dialog instance from the initGui() method to the __init__() method and add the following lines like so:

self.dlg=qgisSpectreDockWidget(self.iface.mainWindow())
if self.dlg.isVisible():
    self.dlg.close()

Also in the __init__() method, change:

self.pluginIsActive = False

to:

self.pluginIsActive = None

Then set the self.pluginIsActive attribute to False in the initGui() method.

Answer 2

Now (November 2023, QGIS v 3.32) I noticed a similiar problem. A kind of "ghosty" dialog will show up after installation. That is the dialog without a background. Ben's solution did not help, but I noticed that after I had closed the widget once, it did not turn up again, so I just unconditionally close the widget in the init, so now the start of the init is

    self.iface = iface
    self.dlg=qgisSpectreDockWidget(self.iface.mainWindow())
    # stops it from showing up when starting QGIS
    #if self.dlg.isVisible():
    try:    
        self.dlg.close()
    except:
        print("Should not be open here")
        # It should not open when QGIS is started
    self.pluginIsActive = None

I wrapped the close() in a try except in case it fails out for some reason. As it probably already is closed, I just catch the exception without any further handling.