Pane tab label cropped on activation

Issue Report Checklist

• Searched the issues page for similar reports
• Read the relevant sections of the Spyder Troubleshooting Guide and followed its advice
• Reproduced the issue after updating with conda update spyder (or pip, if not using Anaconda)
• Tried basic troubleshooting (if a bug/error)
  • Restarted Spyder
  • Reinstalled the latest version of Anaconda
  • Tried the other applicable steps from the Troubleshooting Guide
• Completed the Problem Description, Steps to Reproduce and Version sections below

Problem Description

When activating a pane, the width of the tab is a bit too small (see the “Find” tab):

However, after a restart (or closing and opening again), it is back to its correct size (also showing that this is a general problem as the breakpoints tab show the same behaviour):

(I seem to recall some issue that may be related to this, but I cannot seem to find it now…)

What steps reproduce the problem?

1. Start a new session
2. Open a tab/pane which has not been opened

What is the expected output? What do you see instead?

Correct size first time it is started.

Versions

• Spyder version: 4.0.0.dev0 (works in 3.3.4 but there is much more spacing there so hard to tell…)
• Python version: 3.7.3
• Qt version: 5.9.6
• PyQt version: 5.9.2
• Operating System name/version: Windows 10

Dependencies

pygments >=2.0    :  2.4.2 (OK)
qdarkstyle >=2.6.4:  2.7 (OK)
sphinx >=0.6.6    :  2.1.0 (OK)
pyls >=0.27.0     :  0.27.0 (OK)
nbconvert >=4.0   :  5.5.0 (OK)
pandas >=0.13.1   :  0.24.2 (OK)
numpy >=1.7       :  1.16.4 (OK)
sympy >=0.7.3     :  1.4 (OK)
cython >=0.21     :  0.29.10 (OK)
qtconsole >=4.5.0 :  4.5.1 (OK)
IPython >=4.0     :  7.5.0 (OK)
matplotlib >=2.0.0:  3.1.0 (OK)
pylint >=0.25     :  2.3.1 (OK)

[ccordoba12]

@goanpeca, please take a look at this one.

[ccordoba12]

Closing because this should be fixed in the next QDarkstyle release.