refactor: buttons and friends (#6102)

src/widgets/buttons/DimButton.hpp

@@ -0,0 +1,40 @@
+#pragma once
+
+#include "widgets/buttons/Button.hpp"
+
+namespace chatterino {
+
+/// @brief A button with a #dim() setting for controlling the opacity of its
+/// content.
+///
+/// This button doesn't paint anything.
+///
+/// @sa #currentContentOpacity()
+class DimButton : public Button
+{
+public:
+    enum class Dim : std::uint8_t {
+        /// Fully opaque (100% opcaity)
+        None,
+        /// Slightly transparent (70% opacity)
+        Some,
+        /// Almost transparent (15% opacity)
+        Lots,
+    };
+
+    DimButton(BaseWidget *parent = nullptr);
+
+    /// Returns the current dim level.
+    [[nodiscard]] Dim dim() const noexcept;
+
+    /// Setter for #dim()
+    void setDim(Dim value);
+
+    /// Returns the current opacity based on the current dim level.
+    [[nodiscard]] qreal currentContentOpacity() const noexcept;
+
+private:
+    Dim dim_ = Dim::Some;
+};
+
+}  // namespace chatterino