handle nil width for button widget

frontend/ui/button.lua

@@ -23,6 +23,9 @@ function Button:init()
 		face = Font:getFace(self.text_font_face, self.text_font_size)
 	}
 	local text_size = text_widget:getSize()
+	if self.width == nil then
+		self.width = text_size.w
+	end
 	-- set FrameContainer content
 	self[1] = FrameContainer:new{
 		margin = self.margin,

frontend/ui/widget.lua

@@ -206,7 +206,7 @@ FrameContainer = WidgetContainer:new{
 }
 
 function FrameContainer:getSize()
-	local content_size =self[1]:getSize()
+	local content_size = self[1]:getSize()
 	return Geom:new{
 		w = content_size.w + ( self.margin + self.bordersize + self.padding ) * 2,
 		h = content_size.h + ( self.margin + self.bordersize + self.padding ) * 2