wimp/window_frame
A WIMP-style window frame.
........................ <─ Resize sensor
.┌────────────────────┐.
.│ Window [o][x]│. <─ Window frame header, drag sensor and control buttons
.├────────────────────┤.
.│'''''''''''''''''''^│. <- ': Viewport #1
.│' '║│.
.│' '║│.
.│' '║│.
.│' '║│.
.│'''''''''''''''''''v│.
.│<═════════════════> │. <─ Optional scroll bars
.└────────────────────┘.
........................