gtk/tk: Ensure no flicker when hovering over images. #17989
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When the mouse is over an image, the status message is two lines long. This causes the toolbar to increase size slightly. On Qt, this is ignored by a sizing policy, but there is no such thing in other toolkits. On GTK this steals space from the canvas, so it re-draws a little bit smaller, until the mouse moves off the image. On Tk, the space is added to the window, _unless_ the window is maximized, and then it's stolen from the canvas as well. As a simple workaround, we add an additional label with invisible text (spaces) on two lines. This forces the toolbar to always be two lines high and thus not flicker. If the message were 3 or more lines long, then the same thing would happen, but we don't have any of those by default. The advantage of using a label is that it saves us having to measure text in some toolkit-specific way, and thus works regardless of theme.
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Note, I also made the message in the GTK toolbar I think this multi-line status message is new in 3.3. |
tacaswell
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jkseppan
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meeseeksmachine
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…989-on-v3.3.x Backport PR #17989 on branch v3.3.x (gtk/tk: Ensure no flicker when hovering over images.)
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PR Summary
When the mouse is over an image, the status message is two lines long. This causes the toolbar to increase size slightly. On Qt, this is ignored by a sizing policy, but there is no such thing in other toolkits. On GTK this steals space from the canvas, so it re-draws a little bit smaller, until the mouse moves off the image. On Tk, the space is added to the window, unless the window is maximized, and then it's stolen from the canvas as well.
As a simple workaround, we add an additional label with invisible text (spaces) on two lines. This forces the toolbar to always be two lines high and thus not flicker. If the message were 3 or more lines long, then the same thing would happen, but we don't have any of those by default. The advantage of using a label is that it saves us having to measure text in some toolkit-specific way, and thus works regardless of theme.
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