windows controls left: Negativ content with

[Anders Magnus Andersen]

When using "left" window controls gnome tweaks opens a distorted menu without a drawn Top Bar and missing side menu, until resized.

```
mars 07 20:17:57 idea gnome-tweaks[11027]: Negative content width -23 (allocation 1, extents 12x12) while allocating gadget (node label, owner GtkLabel)
mars 07 20:17:57 idea gnome-tweaks[11027]: gtk_widget_size_allocate(): attempt to allocate widget with width -11 and height 19
mars 07 20:17:57 idea gnome-tweaks[11027]: Negative content width -23 (allocation 1, extents 12x12) while allocating gadget (node label, owner GtkLabel)
mars 07 20:17:57 idea gnome-tweaks[11027]: gtk_widget_size_allocate(): attempt to allocate widget with width -11 and height 19
mars 07 20:17:57 idea gnome-tweaks[11027]: Negative content width -23 (allocation 1, extents 12x12) while allocating gadget (node label, owner GtkLabel)
mars 07 20:17:57 idea gnome-tweaks[11027]: gtk_widget_size_allocate(): attempt to allocate widget with width -11 and height 19
mars 07 20:17:57 idea gnome-tweaks[11027]: Negative content width -23 (allocation 1, extents 12x12) while allocating gadget (node label, owner GtkLabel)
mars 07 20:17:57 idea gnome-tweaks[11027]: gtk_widget_size_allocate(): attempt to allocate widget with width -11 and height 19
mars 07 20:17:57 idea gnome-tweaks[11027]: Negative content width -23 (allocation 1, extents 12x12) while allocating gadget (node label, owner GtkLabel)
mars 07 20:17:57 idea gnome-tweaks[11027]: gtk_widget_size_allocate(): attempt to allocate widget with width -11 and height 19

```

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-tweaks 3.34.0-2
ProcVersionSignature: Ubuntu 5.4.0-17.21-generic 5.4.22
Uname: Linux 5.4.0-17-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu18
Architecture: amd64
CurrentDesktop: GNOME
Date: Sat Mar 7 20:19:07 2020
InstallationDate: Installed on 2020-03-03 (3 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Alpha amd64 (20200303)
PackageArchitecture: all
SourcePackage: gnome-tweaks
UpgradeStatus: No upgrade log present (probably fresh install)