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LWXGL supports a single modal dialog overlay that is rendered on top of all other elements. While a modal is open the event system returns early from button and input handling — clicks on buttons and keystrokes into input fields are suppressed — so the modal acts as a true blocking layer. Two types are supported: OK-only (type 0) and OK/Cancel (type 1).

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Spawning a Modal

void GSpawnModal(int type, const char* msg, void (*on_confirm)(void));
Displays a modal dialog with the given message and an optional confirmation callback.
ParameterDescription
type0 for an OK-only dialog; 1 for an OK/Cancel dialog.
msgMessage text displayed inside the dialog. Supports \n for explicit line breaks. Lines are also soft-wrapped at approximately 31 characters.
on_confirmCalled when the user clicks OK. Pass NULL if no action is needed on confirm.
Clicking Cancel (type 1 only) dismisses the modal without calling on_confirm.

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Example — save confirmation dialog

#include <stdio.h>
#include "libLWXGL.h"

void do_save(void) {
    printf("Saving...\n");
    // perform save logic here
}

void on_save_click(void) {
    GSpawnModal(1, "Save changes before closing?", do_save);
}

// In setup:
GCreateButton(0, 20, 20, 140, 30, 0x78, 0x87, 0x00, "Save & Close", on_save_click);

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Checking Modal State

int GQueryModalOpen(void);
Returns 1 if a modal is currently visible, 0 otherwise. This is useful in event handlers and frame callbacks to avoid triggering secondary actions while the user is interacting with a dialog.

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Example — guard a button callback

void on_dangerous_action(void) {
    // Prevent re-entry if a modal is already open
    if (GQueryModalOpen()) return;

    GSpawnModal(1, "This cannot be undone.\nAre you sure?", perform_action);
}
You can also use GQueryModalOpen inside the per-frame callback to pause game logic, hide animated overlays, or prevent canvas updates while the modal is on screen: 
void on_frame(int tick) {
    if (GQueryModalOpen()) return; // pause simulation while modal is shown

    update_simulation(tick);
    GClearImage(0, 0);
    draw_frame(tick);
    GUpdateImage(0);
}
The modal is rendered by the internal DrawActiveModal function as a centered 306 × 156 px box with a black fill and a one-pixel white border. Message text is drawn in white starting near the top of the box, left-aligned with a small margin.
  • The OK label is rendered in green (palette index 10) near the bottom-right of the dialog.
  • The Cancel label (type 1 only) is rendered in red (palette index 12) to the left of OK.
Hit-testing for the buttons is performed against fixed pixel regions relative to the horizontal center of the window, so the dialog always appears centered regardless of window width.
Only one modal can be active at a time. Calling GSpawnModal while another modal is already open immediately replaces it — the previous message and on_confirm callback are discarded with no notification.
A common pattern is to use GSpawnModal inside a GEventAttachDelete handler to show a confirmation prompt before allowing the window to close. Pass GDeleteWindow as on_confirm so that clicking OK actually closes the application:
int on_close(void) {
    if (!GQueryModalOpen()) {
        GSpawnModal(1, "Quit the application?", GDeleteWindow);
    }
    return 0; // cancel the close, let modal handle it
}
Returning 0 from the delete handler keeps the window alive. If the user clicks OK in the modal, GDeleteWindow is called directly, setting the close flag and exiting the main loop cleanly.

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