gui2: Create a definition for windows without border decorations

data/gui/default/widget/window_borderless.cfg

@@ -0,0 +1,103 @@
+#textdomain wesnoth-lib
+###
+### Definition of borderless dialogs (e.g. lobby).
+###
+
+#define _GUI_RESOLUTION_OPAQUE_SIMPLE RESOLUTION BORDER_SIDE_1 BORDER_SIDE_2
+	[resolution]
+
+		{RESOLUTION}
+
+		left_border = {BORDER_SIDE_1}
+		right_border = {BORDER_SIDE_2}
+		top_border = {BORDER_SIDE_1}
+		bottom_border = {BORDER_SIDE_2}
+
+		[background]
+
+			[draw]
+
+				[image]
+					x = 0
+					y = 0
+					w = "(width)"
+					h = "(height)"
+					name = "dialogs/opaque-background.png"
+					resize_mode = "tile"
+				[/image]
+
+			[/draw]
+
+		[/background]
+
+		[foreground]
+
+			[draw]
+			[/draw]
+
+		[/foreground]
+
+		[grid]
+
+			[row]
+				grow_factor = 1
+				[column]
+					horizontal_grow = "true"
+					vertical_grow = "true"
+					[scrollbar_panel]
+						vertical_scrollbar_mode = "initial_auto"
+						horizontal_scrollbar_mode = "initial_auto"
+						[definition]
+
+							[row]
+
+								[column]
+									horizontal_grow = "true"
+									vertical_grow = "true"
+									[grid]
+										id = "_window_content_grid"
+									[/grid]
+
+								[/column]
+
+							[/row]
+
+						[/definition]
+
+					[/scrollbar_panel]
+
+				[/column]
+
+			[/row]
+
+			[row]
+
+				[column]
+
+					[button]
+						id = "click_dismiss"
+						definition = "default"
+
+						label = "Close"
+					[/button]
+
+				[/column]
+
+			[/row]
+
+		[/grid]
+
+	[/resolution]
+#enddef
+
+[window_definition]
+
+	id = borderless
+	description = "A simple window without border decorations."
+
+	{_GUI_RESOLUTION_OPAQUE_SIMPLE ({GUI_TINY__RESOLUTION})  5  6 }
+	{_GUI_RESOLUTION_OPAQUE_SIMPLE ()                       10 13 }
+
+[/window_definition]
+
+#undef _GUI_RESOLUTION_OPAQUE_SIMPLE