waybar: allow setting layer to overlay

[chayleaf]

Description

This is undocumented, but this allows showing the bar above all windows, including fullscreen ones.

Checklist

• Change is backwards compatible.

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Maintainer CC

@berbiche

[stale]

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[chayleaf]

this is still ready for merging

[teto]

could you share any reference where it's used ? maybe it's not part of the doc because it's not intended to be used (aka experimental feature ?). Also you should rebase to fix CI

[chayleaf]

I don't understand what you mean by examples, the code is just

void from_json(const Json::Value& j, std::optional<bar_layer>& l) {
  if (j == "bottom") {
    l = bar_layer::BOTTOM;
  } else if (j == "top") {
    l = bar_layer::TOP;
  } else if (j == "overlay") {
    l = bar_layer::OVERLAY;
  }
}

void waybar::Bar::setMode(const struct bar_mode& mode) {
  // ...
  if (mode.layer == bar_layer::BOTTOM) {
    gtk_layer_set_layer(gtk_window, GTK_LAYER_SHELL_LAYER_BOTTOM);
  } else if (mode.layer == bar_layer::TOP) {
    gtk_layer_set_layer(gtk_window, GTK_LAYER_SHELL_LAYER_TOP);
  } else if (mode.layer == bar_layer::OVERLAY) {
    gtk_layer_set_layer(gtk_window, GTK_LAYER_SHELL_LAYER_OVERLAY);
  }
  // ...
}

I use this in my personal config on my phone because the bar has UI controls so it's hidden I can't open the menu, so it has to stay on top of all windows.