double click not opening new tab

**Describe the bug**

Double clicking on the "tab bar" (i.e. where the open tabs live) no longer opens a new tab.

**Expected behavior**

In all previous versions of Guake I've used, double clicking on the tab bar opens a new terminal/tab.

**Actual behavior**

Nada. Nothing. Zip. (i.e., no new tab!)

**To Reproduce**

Double click on tab bar.

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$ screenfetch; lsb_release -a; uname -a
No value set for `/apps/metacity/general/theme'
user@gigabyte
OS: Ubuntu 20.04 focal
Kernel: x86_64 Linux 5.4.0-29-generic
Uptime: 1d 2h 46m
Packages: 2702
Shell: bash 5.0.16
Resolution: 7840x2560
DE: GNOME 3.36.2
WM: Metacity
GTK Theme: Yaru [GTK2/3]
Icon Theme: ubuntu-mono-light
Font: Ubuntu 11
Disk: 2.2T / 3.7T (62%)
CPU: Intel Core i5-3570K @ 4x 3.8GHz [48.0°C]
GPU: GeForce GTX 650 Ti BOOST
RAM: 15156MiB / 24014MiB
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04 LTS
Release: 20.04
Codename: focal
Linux gigabyte 5.4.0-29-generic #33-Ubuntu SMP Wed Apr 29 14:32:27 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

$ guake --support
$ guake --support

Guake Version: 3.7.1

Vte Version: 0.60.1

Vte Runtime Version: 0.60.1

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GTK+ Version: 3.24.18

GDK Backend: GdkX11.X11Display

--------------------------------------------------
Desktop Session: gnome-flashback-metacity

--------------------------------------------------
Display: :0

RGBA visual: True

Composited: True

* Monitor: 0 - HYO DVI-I-1
* Geometry: 2560 x 1440 at 1920, 423
* Size: 597 x 336 mm²
* Primary: True
* Refresh rate: 59.95 Hz
* Subpixel layout: unknown
* Monitor: 1 - DEL HDMI-0
* Geometry: 1920 x 1080 at 0, 783
* Size: 531 x 299 mm²
* Primary: False
* Refresh rate: 60.00 Hz
* Subpixel layout: unknown
* Monitor: 2 - SAM DP-0
* Geometry: 1920 x 1080 at 5920, 1480
* Size: 477 x 268 mm²
* Primary: False
* Refresh rate: 60.00 Hz
* Subpixel layout: unknown
* Monitor: 3 - HYO DVI-D-0
* Geometry: 1440 x 2560 at 4480, 0
* Size: 597 x 336 mm²
* Primary: False
* Refresh rate: 59.95 Hz
* Subpixel layout: unknown