WorkflowEditor and WorkflowLauncher have display problems with dark themes on Linux

In the case of WorkflowEditor, the area where the workflow is drawn is too dark. On the contrary, WorkflowLaunches has problems with the preset light backgrounds, since on Linux, when using a dark theme, text is also written in white color. Consequently, it is not possible to see the information shown in the three tabs (parameters, files, repositories).