Make some widget constructors explicit

dgl/ImageButton.hpp

@@ -34,11 +34,11 @@ public:
         virtual void imageButtonClicked(ImageButton* imageButton, int button) = 0;
     };
 
-    ImageButton(Window& parent, const Image& image) noexcept;
-    ImageButton(Window& parent, const Image& imageNormal, const Image& imageHover, const Image& imageDown) noexcept;
-    ImageButton(Widget* widget, const Image& image) noexcept;
-    ImageButton(Widget* widget, const Image& imageNormal, const Image& imageHover, const Image& imageDown) noexcept;
-    ImageButton(const ImageButton& imageButton) noexcept;
+    explicit ImageButton(Window& parent, const Image& image) noexcept;
+    explicit ImageButton(Window& parent, const Image& imageNormal, const Image& imageHover, const Image& imageDown) noexcept;
+    explicit ImageButton(Widget* widget, const Image& image) noexcept;
+    explicit ImageButton(Widget* widget, const Image& imageNormal, const Image& imageHover, const Image& imageDown) noexcept;
+    explicit ImageButton(const ImageButton& imageButton) noexcept;
 
     void setCallback(Callback* callback) noexcept;
 

dgl/ImageKnob.hpp

@@ -41,9 +41,9 @@ public:
         virtual void imageKnobValueChanged(ImageKnob* imageKnob, float value) = 0;
     };
 
-    ImageKnob(Window& parent, const Image& image, Orientation orientation = Vertical, int id = 0) noexcept;
-    ImageKnob(Widget* widget, const Image& image, Orientation orientation = Vertical, int id = 0) noexcept;
-    ImageKnob(const ImageKnob& imageKnob);
+    explicit ImageKnob(Window& parent, const Image& image, Orientation orientation = Vertical, int id = 0) noexcept;
+    explicit ImageKnob(Widget* widget, const Image& image, Orientation orientation = Vertical, int id = 0) noexcept;
+    explicit ImageKnob(const ImageKnob& imageKnob);
     ~ImageKnob() override;
 
     int getId() const noexcept;

dgl/ImageSlider.hpp

@@ -36,9 +36,9 @@ public:
         virtual void imageSliderValueChanged(ImageSlider* imageSlider, float value) = 0;
     };
 
-    ImageSlider(Window& parent, const Image& image, int id = 0) noexcept;
-    ImageSlider(Widget* widget, const Image& image, int id = 0) noexcept;
-    ImageSlider(const ImageSlider& imageSlider) noexcept;
+    explicit ImageSlider(Window& parent, const Image& image, int id = 0) noexcept;
+    explicit ImageSlider(Widget* widget, const Image& image, int id = 0) noexcept;
+    explicit ImageSlider(const ImageSlider& imageSlider) noexcept;
 
     int getId() const noexcept;
     void setId(int id) noexcept;