Guake does not display images when w3m-img is installed

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For how to run the latest Guake in your computer, please refer to [Install from source](https://guake.readthedocs.io/en/latest/user/installing.html#install-from-source).

**Describe the bug**

Guake does not display images when w3m-img is installed

**Expected behavior**

Google Logo appears

**Actual behavior**

Text only

**To Reproduce**

Install w3m and w3m-img through your package manager, then run `w3m google.com` in both Guake and another terminal (Konsole in this case)

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Please run `$ guake --support`, and paste the results here. Don't put backticks (`` ` ``) around it! The output already contains Markdown formatting. And make sure you run the command **OUTSIDE** the Guake.

$ guake --support

Guake Version: 3.6.3

Vte Version: 0.60.3

Vte Runtime Version: 0.60.3

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GTK+ Version: 3.24.20

GDK Backend: GdkX11.X11Display

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Desktop Session: plasma

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Display: :0

RGBA visual: True

Composited: True

* Monitor: 0 - DEL HDMI-0
* Geometry: 1920 x 1080 at 0, 0
* Size: 509 x 286 mm²
* Primary: True
* Refresh rate: 60.00 Hz
* Subpixel layout: unknown