Fix OMShell Unreadable Text Under Dark Themes A Comprehensive Guide

by StackCamp Team 68 views

Have you ever encountered the frustration of using a dark theme on your operating system, only to find that certain applications become virtually unreadable? One such issue plagues users of OpenModelica's OMShell under dark themes, where the text blends seamlessly into the background, rendering it invisible. In this article, we'll dive deep into this problem, explore its root cause, and provide a step-by-step solution to make OMShell readable again.

Understanding the OMShell Dark Theme Problem

The OMShell text unreadability issue arises when using dark themes on both KDE (Linux) and macOS. The problem is that the text and background colors are both set to white, making the text disappear against the light backdrop. This issue significantly hinders the usability of OMShell, as users cannot read or interact with the interface effectively.

Steps to Reproduce the Issue

  1. On KDE (Linux):
    • Open "System Settings".
    • Go to the "Quick Settings" page.
    • Select the "Breeze Dark" global theme.
    • Apply the changes.
  2. On macOS:
    • Open "System Settings".
    • Navigate to the "Appearance" page.
    • Choose the "Dark" theme.
  3. Open OMShell: Launch the OMShell application.

Observed Behavior

Upon opening OMShell under a dark theme, you'll notice that the text is barely visible, if at all. Both the text and background appear white, creating a stark contrast that makes reading impossible. Unless you select the text, it remains unreadable, which is far from ideal for a command-line interface.

Version and OS Information

This issue has been observed in:

  • OpenModelica Version: v1.26.0-dev-219-g66f8a832fc-cmake (also observed on 1.25.1 Debian/Ubuntu packages)
  • Operating Systems:
    • macOS 15
    • KDE with Qt 6.8

Diving into the Root Cause: Hardcoded Background Color

The root cause of this problem lies in a hardcoded background color selection within the OMShell's codebase. Specifically, the relevant code can be found in OMShell/OMShell/OMShellGUI/ starting at line 226. The code snippet in question is:

// set frame backgroundcolor
QPalette palette;
palette.setColor( QPalette::Base, QColor(255,255,255) );
mainFrame_->setPalette( palette );

This code explicitly sets the background color to white (QColor(255,255,255)), regardless of the system's theme settings. Interestingly, this code has been present since the initial commit of qms.cpp back in 2006, under Qt4. It appears that this hardcoded color, while suitable for light themes, clashes severely with dark themes, leading to the unreadability issue.

Impact of Removing the Hardcoded Color

Interestingly, suppressing these lines of code appears to resolve the issue on both KDE and macOS. By removing the hardcoded background color, OMShell can inherit the system's theme settings, resulting in readable text under dark themes. However, it's crucial to test this solution across different platforms, including Windows, to ensure compatibility.

Workaround: Using Qt Stylesheets to Fix OMShell Dark Theme

While a code-level fix is the ideal solution, a practical workaround exists for users facing this issue right now. The Qt --stylesheet command-line option allows you to override the hardcoded color selection, providing a temporary fix until a permanent solution is implemented. Here's how to implement this workaround:

Step-by-Step Guide to Implementing the Workaround

  1. Create a CSS File:
    • Create a new text file and name it, for example, omshell_background_fix.css. You can choose any name, but make sure the extension is .css.
  2. Add CSS Code:

    • Open the omshell_background_fix.css file in a text editor.

    • Add the following CSS code:

      QPlainTextEdit { background-color: dimgray }

      In this code, dimgray is used as the background color. You can replace it with any suitable color you prefer. Darker shades like dimgray, darkgray, or even a custom hexadecimal color code like #333333 are good choices for dark themes.

  3. Save the File:
    • Save the omshell_background_fix.css file in a location where you can easily access it. Your home directory or a dedicated folder for stylesheets are good options.
  4. Launch OMShell with the Stylesheet:

    • Open your terminal or command prompt.

    • Navigate to the directory where OMShell is installed.

    • Run the following command:

      OMShell --stylesheet path/to/omshell_background_fix.css

      Replace path/to/omshell_background_fix.css with the actual path to the CSS file you created. For example, if the file is in your home directory, the command might look like this:

      OMShell --stylesheet /home/yourusername/omshell_background_fix.css
  5. Verify the Fix:
    • Once OMShell launches, you should see that the background color has changed according to the CSS you specified. The text should now be clearly readable against the new background color.

Benefits of Using the Stylesheet Workaround

  • Immediate Solution: This workaround provides an immediate solution to the unreadability issue, allowing you to use OMShell comfortably under dark themes.
  • Customizable: You can easily customize the background color by changing the value in the CSS file. This allows you to choose a color that suits your preferences and provides optimal readability.
  • Non-Invasive: This workaround doesn't require modifying the OMShell's code directly, making it a safe and reversible solution.

Additional Considerations and Related Issues

While the stylesheet workaround effectively addresses the main issue, there are a few additional considerations and related problems to be aware of:

OMEdit's