added static checks to d2ui (#990)

Co-authored-by: M. Sz <mszeptuch@protonmail.com>

d2core/d2ui/button.go

@@ -768,7 +768,8 @@ func getButtonLayouts() map[ButtonType]ButtonLayout {
 	}
 }
 
-var _ Widget = &Button{} // static check to ensure button implements widget
+// static check to ensure button implements clickable widget
+var _ ClickableWidget = &Button{}
 
 // Button defines a standard wide UI button
 type Button struct {

d2core/d2ui/checkbox.go

@@ -6,8 +6,8 @@ import (
 	"github.com/OpenDiablo2/OpenDiablo2/d2common/d2resource"
 )
 
-// static check that Checkbox implements Widget
-var _ Widget = &Checkbox{}
+// static check that Checkbox implements ClickableWidget
+var _ ClickableWidget = &Checkbox{}
 
 // Checkbox represents a checkbox UI element
 type Checkbox struct {

d2core/d2ui/label.go

@@ -11,6 +11,9 @@ import (
 	"github.com/OpenDiablo2/OpenDiablo2/d2common/d2util"
 )
 
+// static check if Label implemented Widget
+var _ Widget = &Label{}
+
 // Label represents a user interface label
 type Label struct {
 	*BaseWidget

d2core/d2ui/scrollbar.go

@@ -13,8 +13,8 @@ const (
 	scrollbarWidth         = 10
 )
 
-// static check that Scrollbar implements widget
-var _ Widget = &Scrollbar{}
+// static check that Scrollbar implements clickable widget
+var _ ClickableWidget = &Scrollbar{}
 
 // Scrollbar is a vertical slider ui element
 type Scrollbar struct {

d2core/d2ui/sprite.go

@@ -11,6 +11,9 @@ import (
 	"github.com/OpenDiablo2/OpenDiablo2/d2common/d2util"
 )
 
+// static check if Sprite implemented Widget
+var _ Widget = &Sprite{}
+
 // Sprite is a positioned visual object.
 type Sprite struct {
 	*BaseWidget

d2core/d2ui/textbox.go

@@ -11,8 +11,8 @@ import (
 	"github.com/OpenDiablo2/OpenDiablo2/d2common/d2util"
 )
 
-// static check that TextBox implements widget
-var _ Widget = &TextBox{}
+// static check that TextBox implements clickable widget
+var _ ClickableWidget = &TextBox{}
 
 // TextBox represents a text input box
 type TextBox struct {