PYTHONPATH Manager opens multiple windows

[mrclary]

Description

What steps will reproduce the problem?

1. Select PYTHONPATH Manager from the toolbar or from the menu bar
2. PYTHONPATH Manager popup window is launched
3. Select again PYTHONPATH Manager from the toolbar or from the menu bar
4. Another PYTHONPATH Manager popup window instance is launched instead of returning focus to original instance

Versions

• Spyder version: 4.2.2
• Python version: 3.9.1
• Qt version: 5.12.10
• PyQt5 version: 5.12.3
• Operating System: Darwin 19.6.0

Dependencies

# Mandatory:
applaunchservices >=0.1.7       :  0.2.1 (OK)
atomicwrites >=1.2.0            :  1.4.0 (OK)
chardet >=2.0.0                 :  4.0.0 (OK)
cloudpickle >=0.5.0             :  1.6.0 (OK)
diff_match_patch >=20181111     :  20200713 (OK)
intervaltree >=3.0.2            :  3.1.0 (OK)
IPython >=7.6.0                 :  7.20.0 (OK)
jedi =0.17.2                    :  0.17.2 (OK)
jsonschema >=3.2.0              :  3.2.0 (OK)
keyring >=17.0.0                :  22.0.1 (OK)
nbconvert >=4.0                 :  6.0.7 (OK)
numpydoc >=0.6.0                :  1.1.0 (OK)
parso =0.7.0                    :  0.7.0 (OK)
pexpect >=4.4.0                 :  4.8.0 (OK)
pickleshare >=0.4               :  0.7.5 (OK)
psutil >=5.3                    :  5.8.0 (OK)
pygments >=2.0                  :  2.8.0 (OK)
pylint >=1.0                    :  2.7.0 (OK)
pyls >=0.36.2;<1.0.0            :  0.36.2 (OK)
pyls_black >=0.4.6              :  0.4.6 (OK)
pyls_spyder >=0.3.2             :  0.3.2 (OK)
qdarkstyle >=2.8                :  2.8.1 (OK)
qtawesome >=0.5.7               :  1.0.2 (OK)
qtconsole >=5.0.1               :  5.0.2 (OK)
qtpy >=1.5.0                    :  1.9.0 (OK)
setuptools >=39.0.0             :  52.0.0 (OK)
sphinx >=0.6.6                  :  3.5.1 (OK)
spyder_kernels >=1.10.2;<1.11.0 :  1.10.2 (OK)
textdistance >=4.2.0            :  4.2.1 (OK)
three_merge >=0.1.1             :  0.1.1 (OK)
watchdog >=0.10.3;<2.0.0        :  1.0.2 (OK)
zmq >=17                        :  22.0.3 (OK)

# Optional:
cython >=0.21                   :  None (NOK)
matplotlib >=2.0.0              :  None (NOK)
numpy >=1.7                     :  None (NOK)
pandas >=1.1.1                  :  None (NOK)
scipy >=0.17.0                  :  None (NOK)
sympy >=0.7.3                   :  None (NOK)

[dalthviz]

Hi @mrclary thanks for the feedback! I was able to reproduce this, and I think the reason is basically that for the path manager the dialog is created every time you click/trigger the action (in comparison for example with the preferences dialog where you only have one instance at a time). Probably we should use some sort of single instance that is created and then maintained/updated to prevent this to happen (or something similar to what is being done for the preferences dialog). What do you guys think @spyder-ide/core-developers ?

[ccordoba12]

I think @mrclary is right and we should only show one instance of that dialog even if users click on that button multiple times.