### Problem description
There are some recent issues about Mac keys not configured properly for
the pattern editor. This PR moves all the shortcuts to the shortcut
manager, so they can be edited at will. Even if the key is not
identified correctly it should be possible to use preferred keys for any
action.
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Co-authored-by: Nik <werwolv98@gmail.com>
### Problem description
#### Problem 1
In borderless mode ImHex disables the standard macOS titlebar rendering
and input processing. As a result double clicking the titlebar does not
trigger the native macOS behavior set in `System Settings -> Desktop &
Dock -> Double-click a window's title bar to [Zoom/Minimize/Do
nothing]`.
#### Problem 2
The ImHex window shows up as blank/transparent when de-minimizing it
from the dock.
#### Problem 3
Widgets experience ghost hover inputs from the past position of the
cursor during live resizing.
### Implementation description
ImGui elements consume input events in the order they are drawn. As a
result by "drawing" an `InvisibleButton` over the content area of the
titlebar we can catch unprocessed clicks in the titlebar area.
Connecting this button's double clicks to the native window is then a
trivial endeavour.
The blank windows was caused by the rendering stack clearing the GL
buffer, but proceeding to draw nothing in it. I have short circuited
this path.
Ghost hover inputs were squelched by consistently moving the ImGui
cursor to `0, 0` during a live resize. The OS will dispatch a cursor
positioning event once the resizing ends, restoring normal behavior.
### Screenshots
N/A
### Additional things
N/A
---------
Co-authored-by: Nik <werwolv98@gmail.com>
### Problem description
When the close button is clicked, `ImGui::BeginPopupModal()` sets the
bool passed into the second parameter (p_open) to false. However, the
closing logic did not take this into account, making it difficult to
actually close modal popups.
For example, closing the "Export pattern File" modal took several clicks
on the "X" button, now it closes instantly.
### Implementation description
I added an additional check for the `open` variable being `false` in the
logic that checks the closing condition.
### Problem description
The framerate limiter doesn't work when inputs are being sent (eg mouse
cursor moving over the window), because `glfwWaitEventsTimeout` returns
early when it encounters an event.
### Implementation description
I made it sleep for the remaining time when that happens.
